Remove doc/dev_communit markup files completely as they are at the wrong place.
Create a new community page, merging all of doc/dev_community and subsection Code of Conduct into a common place.
The corresponding patch to ffmpeg-web puts the Organisation & Code of Conduct into a seperate community chapter on the FFmpeg website.
Nobody is going to check the queue anymore, so users must now subscribe to
send messages to ffmpeg-devel. This will prevent orphaned/ignored messages
from rotting in the abandoned queue. This matches the behavior of ffmpeg-user
and libav-user.
Also, this addresses some other nits.
Signed-off-by: Lou Logan <lou@lrcd.com>