faq: Add question often asked with regards to standardizing a particular feature

Answer ad-literam taken from
wayland/wayland#99 (comment 186640),
with some minor modifications that adds some examples and clearly
define what the answer is all about.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
1 job for standard-feat in 2 minutes and 21 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Build
passed #481502
libinput

00:02:21