Add governance docs

Add governance docs

Add LFN principles and LFN project lifecycle docs.

This change combines work from 10223, 10221 and 10103 to make the
editing workflow easier. Also, these documents are closely related
changes that need to be worked on and merged together, not atomic
changes that should be handled in smaller commits.

Board approval: https://lists.lfnetworking.org/g/TAC/message/420

Change-Id: I84d362a6b6f42fd7f269f7d7a44199355e4fa9f4
Signed-off-by: Daniel Farrell <dfarrell@redhat.com>
Signed-off-by: Ed Warnicke <hagbard@gmail.com>