many contrib links are broken

The commit 159e3d86292cfec2a2828f9f69ac7a6cb1be242d created some funny
business out of many links to contrib modules.  Take a look at this
page:

http://developer.postgresql.org/pgdocs/postgres/log-shipping-alternative.html

It now reads: "See the Section F.31 module for a reference
implementation of this." (where it previously said "the pg_standby
module")  There are many other places like that now.

I don't think the toolchain changed in this area, so the whole change
was broken to begin with.  The idea is sound, IMO, but the
implementation needs to be reevaluated.