In errata/article.xml, update the document will be maintained

In errata/article.xml, update the document will be maintained
until the EoL of the stable/9 branch.

In share/xml/release.xsl update the recommended mailing list
from -current to -stable.

In share/examples/Makefile.relnotesng, update the branch name
convention from CVS-style to SVN-style.

In installation/article.xml:
 - Use descriptive text for the synching.html and the
   makeworld.html pages to fix how the URLs are displayed.
 - Remove a reference to 7.x.
 - Change a reference from 8.2-RELEASE to 8.4-RELEASE.

In readme/article.xml:
 - Change the recommended mailing list from -current
   to -stable.
 - Replace send-pr(1) references to Bugzilla equivalents.
 - Note that send-pr(1) is a stub shell script now.
 - Use descriptive text in a link to fix the URL.

In share/xml/release.ent:
 - Update release.type from 'snapshot' to 'release.'
 - Set IGNORE on release.type.snapshot, and INCLUDE on
   release.type.release.
 - Update release.manpath.freebsd to 9.3-RELEASE.

Approved by:	re (implicit)
Sponsored by:	The FreeBSD Foundation

git-svn-id: svn://svn.freebsd.org/base/releng/9.3@268417 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f