Update Documentation/fb/fbcon.txt to reflect the following changes:

1. Simple illustration of the binding of the console down to individual
   framebuffer drivers

2. Usage of userspace tools to help with recovery of text console

3. How to use the attributes in /sys/class/tty/console to unload fbcon and
   the framebuffer drivers
Signed-off-by: NAntonino Daplas <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>