pgsql: Add release checklist item: o copy FAQs from HEAD to

Log Message:
-----------
Add release checklist item:

o copy FAQs from HEAD to top-most branches

Modified Files:
--------------
pgsql/src/tools:
RELEASE_CHANGES (r1.66 -> r1.67)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/RELEASE_CHANGES.diff?r1=1.66&r2=1.67)