Stop saying that API is experimental and that only USB is supported,
acknowledge that evdev is the preferred interface, and remove paragraph
encouraging people sending snail mail to Vojtech :) along with his email.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Consolidate use instructions and userspace API notes into the same chapter;
remove completely obsolete references, move into a separate subdirectory.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
