Add a section which defines the input device properties and provides
guidelines on how to use them.
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>
Reviewed-by: NChase Douglas <chase.douglas@canonical.com>
Reviewed-by: NJussi Pakkanen <jussi.pakkanen@canonical.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>