METHOD FOR INSERTING A RIGID DISPLAY MODULE IN CLOTHING OR A FASHION ACCESSORY AND ARTICLE FITTED WITH SUCH A MODULE The invention relates to a method for inserting a rigid display module, in particular controllable scroll-down readout, in clothing or a fashion accessory, and the article thus fitted. The term rigid module here refers to any display module constituted of a shell made in plastic with certain rigidity, ranging from fully rigid to semi-flexible. Rigid display modules are traditionally used in office, shop or restaurant windows or in specific sites to present information relating to the articles, menus, weather conditions or events offered by the businesses or sites. Such modules are miniaturised in order to be placed in specific locations, for example on all the tables in a restaurant. However, no use has been offered with the aim of promoting a piece of clothing via this type of display unit or of using such equipment to transmit information by means of personal and/or marketing messages. The invention aims at resolving this situation by adapting such display units for clothing accessories. To do so, the invention proposes to insert the display module into the clothing accessory via rear covering of this module uniting around an opening. More specifically, the object of the invention is a method for inserting a rigid display module, in particular a controllable scroll-down readout, in a clothing accessory made in flexible material having an external skin, consisting in making an opening window in the skin of the clothing accessory barely smaller than the dimensions of the display module, in introducing the display module from the inside of the accessory opposite the window, in entirely covering the rear section of the module, over at least two sides, with a piece of flexible material forming a sufficiently dimensioned casing to unite along the periphery of the window while tightly fitting the module. Skin means a one-layer tail or panel, or any type of material, fabric or cloth. The skin comprises two faces, and outer face and an inner face, outer and inner refer to the person who wears the cloth. According to particular embodiments: - the casing wraps around the module in a pocket-like manner creating a reinforcement on the display surface of the module along the peripheral edge around the window, the reinforcement uniting with the inner face of the skin of the accessory; - a reinforcement unites with the skin so as to encircle the window and the section of casing stretching beyond the rear face that unites with the external periphery of the reinforcement; - the casing is formed by a section of the skin itself whereas a supplementary piece of material, provided with the window, unites with the outer face of the skin; in this case, the casing section is limited by the outline where the supplementary piece unites with the skin; - the casing is formed by a supplementary piece of material which is united with the inner face of the skin, whereas the window is formed in the section of skin limited by the outline where the supplementary piece unites with the skin; - a slot or a rectangular opening are formed along the main dimension of the casing in order to introduce the display module which is tightly fitted to at least two opposed sides of the casing limited by the outline where the supplementary piece unites with the skin; - the section of casing is cut out to provide access to the means for controlling and powering the display module; - in the event that the accessory has a lining, the latter is cut out to provide access to the inside of the skin opposite the window, then closed up via reversible means such as a zip. The invention also relates to an article, clothing, a fashion accessory or leather articles, fitted with at least a display module according to the above insertion method. According to preferred embodiments of such an accessory: - the material of the casing section is constituted of leather, artificial leather or elastic polymer mixed with natural or synthetic material (cotton, polyester, polyamides, etc.), or by natural or synthetic material wove in such a manner that it gives elasticity to the cloth ; - the uniting of the reinforcement and of the section of casing is accomplished via bonding and/or top stitching; a self-adhesive strip is bonded to the rear face of the display module and the section of casing has a partly self-adhesive face which joins up with the self-adhesive strip prior to uniting with the reinforcement; - the section of casing is partly cut out to provide movable access to the means for controlling and powering the display module. Other advantages and features of the invention will become apparent upon reading the detailed embodiment that follows in reference to the annexed drawings which respectively represent: in figure 1 , an overall view of a jacket fitted with a display module according to the invention; in figure 2, a cross section of means for inserting the display module into the jacket; - in figure 3, a top view of the casing of the display module; - in figures 4a and 4b, front views of respectively the outer and the inner face of the skin according to another embodiment involving the skin as a casing; and in figures 5a and 5b, front views of respectively the outer and the inner face of the skin according to a further embodiment. In reference to figure 1 , an electronic display module 10 is fitted to a leather jacket 20. The display module is integrated into the back 21 of the jacket and the scroll-down message is through an window 30. The means for inserting allow to imbed this module into any type of clothing made in a flexible material but sufficiently solid and thick, such as leather or artificial leather, for example into trousers or a parka. It can also be inserted into any accessory: cap, bag, handbag, briefcase, suitcase, etc. Figure 2 shows a cross section of the inserting of such a display module 10 into a jacket 20. The jacket 20 bears an external skin 22 into which the window 30 is made. The window is rectangular, 14 cm x 4 cm, and is barely smaller, about 7 mm, than the rectangular dimensions of the module 10. The window 30 is reinforced, along a peripheral edge "b" encircling the window, via a rectangular leather cut out 40 whose cut out centre also leans against the window 30. The edge "b" is about a centimetre wide, approximately equal to twice that of the edge 11 of the casing of the module 10. The reinforcement is bonded and top stitched onto the inner face 2 of the skin 22. In the event that the module has no casing, the reinforcement 40 simply covers the perimeter of the module without covering the scroll-down message. The display module 10 is then centred from the inside of the skin 22 of the jacket, opposite the window. The edge 11 of the module 10 is then bonded to the cut out reinforcement 40 edge-to-edge. A self-adhesive strip 50 is bonded to the rear face 12 of the display module 10 out with the access zones to the means for programming and powering. A section of casing 60 made in leather covers the rear face 12. One face 61 of the section of casing 60 is partly self-adhesive and joins up with the self-adhesive strip 50. The section of casing 60 extends beyond the structure created by the rear face 12 on three sides (two of the three overlapping sides being represented in figure 2). The edges of this casing 60 unite with the reinforcement 40 via bonding and top stitching. According to figure 3, the casing 60 is partly cut out so as to allow, via raising, movable access to the means for programming and powering the display module. The closing up of the thus cut out tabs 62 is done thanks to the self-adhesive sections. The jacket 20 has a lining 24 which is cut out to provide access to the inner face 2 of the skin 22 opposite the window 30. This cut out section is fitted with a zip 26 to create a reversible access. The invention is not restricted to the embodiment described and represented. The section of casing can create a pocket in which the display module is inserted, this pocket bearing an window corresponding with the window made in the clothing or accessory. The edges of the window of the pocket are united with the periphery of the corresponding window of this clothing or accessory, in the same manner as the reinforcement described in the detailed example. The back of the pocket is then cut out to provide access to the means for controlling and electric powering. Self-adhesive strips can be envisaged to render the cut out sections in the back of the pocket reversible. Moreover it is possible to do without the self-adhesive layers, notably when the module is thin, for example 2 to 3 mm. When the cloth has a skin in a material sufficiently elastic, for instance natural and/or synthetic material (cotton, polyester, polyamides, or equivalent, etc.), especially for tee shirts or sweatshirts, the casing section is formed: - as illustrated by figures 4a and 4b, by a portion 22a of the skin itself 22 (figure 4b) wherein a slot 40a is provided in order to introduce the display module 10; a supplementary piece of material 41 (figure 4a), provided with a coloured window 30 stitched on the rims of an opening 42, unites by stitching the outer face F1 of the skin 22; the casing section is limited by the outline 43 of the supplementary piece, i.e. where the supplementary piece 41 unites with the skin along the stitched line, in order to tightly fit the display module 10; as illustrated by figures 5a and 5b, by a supplementary piece of material 50(figure 5b) provided with a rectangular opening 50a, in order to introduce the display module 10; this supplementary piece of material is united with the inner face F2 of the skin 22, whereas the opening 52 is formed in the section of skin 22 limited by the stitched outline 53 where the supplementary piece unites with the skin and tightly fits the display module 10. The casing is provided with either a slot or a rectangular opening, or any type of opening aimed to introduce the display module. Additionally, any means for uniting can be used: tacks, snap fasteners, binding paste, stitch, glue, melting, fusing, etc. Moreover, the window can be made of plastic material, transparent with or without additional colour, or can be letting as an opening, i.e. a hole, when the display module is considered protected by itself. Furthermore, the means for controlling and programming can be integrated into a remote control, the command signals being received by a detector of the emitted waves, for example an infrared detector, integrated into the display module.