[documentation] security forum/feed split plan.

[Peter Wolanin]

Based on the DCDC security team BoF and discussions with Gábor and
general sign-off from Heine and other security team members yesterday,
below is a plan that I will carry forward and execute (with your help)
in the coming day or so.  The goal of this plan is to more clearly
distinguish core and contrib security issues and make the good record
of Drupal core more apparent.  If you feel that there are serious
problems with the plan, please write back as soon as possible.

All existing SAs will be divided among 3 forums:

- Drupal core security advisories
- Contributed project security advisories
- Security public service announcements

Since there are fewer core SAs and PSAs than contrib SAs, we'll make
two new forums for core and PSAs and move the existing forum nodes to
those.  It appears that the lists module that is part of the drupalorg
project will support multiple forum tids going to a single list, so
after the topics are moved someone with root access will just need to
edit settings.php to add the new tids to the settings array.

These 2 aliases will be pointed to the new core SA forum tid taxonomy page/feed:
http://drupal.org/security
http://drupal.org/security/rss.xml

We will add new aliases for the other tids like:

http://drupal.org/contrib-security
http://drupal.org/contrib-security/rss.xml
http://drupal.org/security-psa
http://drupal.org/security-psa/rss.xml

All 3 of the taxonomy pages will get the 3 blocks currently on
http://drupal.org/security

For the short term at least, the block at the top left will just
contain links to all 3 pages and feeds.  In the longer term, we might
do something more clever like add tabs to the /security page

Probably some minor handbook changes will be needed to reflect this
re-organization.

-Peter