XBitMap support (*.xbm) description
XBitMap support (*.xbm) description

Add description of XBitMap support extension.
ubidefeo/Adafruit-GFX-Library,jeroavf/Adafruit-GFX-Library,labsud/Adafruit-GFX-Library,daniel3514/Adafruit-GFX-Library,daniel3514/Adafruit-GFX-Library,bryanmwhite/Adafruit-GFX-Library,leighmurray/GFX-Sharp,venusdharan/Adafruit-GFX-Library,yangjae/Adafruit-GFX-Library,labsud/Adafruit-GFX-Library,ubidefeo/Adafruit-GFX-Library,jeroavf/Adafruit-GFX-Library,ConnDuino/ConnDuino-GFX-Library,leighmurray/GFX-Sharp,yangjae/Adafruit-GFX-Library,bryanmwhite/Adafruit-GFX-Library,venusdharan/Adafruit-GFX-Library,sstocker46/Adafruit-GFX-Library,sstocker46/Adafruit-GFX-Library,ConnDuino/ConnDuino-GFX-Library