Update bind-8.1 docs in FAQ.

Update known_bugs with 1.2.1 relevance.
Remove some 192.168.x.x host references in known_bugs.
Add note about sunos 4.x and KeepAlive off.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@78406 13f79535-47bb-0310-9956-ffa450edef68