This backatches Heikki's patch in 140a4fbf1a
to make sure the documentation on the website gets updated, since
we're regularly receiving complains about this link.
<!-- $PostgreSQL: pgsql/doc/src/sgml/README.links,v 1.3 2009/01/10 16:58:39 momjian Exp $ -->
Linking within SGML documents can be confusing, so here is a summary:
Intra-document Linking
----------------------
<xref>
use to get link text from the title of the target link; has no
close tag
http://www.oasis-open.org/docbook/documentation/reference/html/xref.html
<link>
use to supply text for the link, requires </link>
http://www.oasis-open.org/docbook/documentation/reference/html/link.html
linkend=
controls the target of the link/xref, required
endterm=
for <xref>, allows the text of the link/xref to be taken from a
different link target title
External Linking
----------------
<ulink>
like <link>, but uses a URL (not a document target); requires
</ulink>; if no text is specified, the URL appears as the link text
http://www.oasis-open.org/docbook/documentation/reference/html/ulink.html
url=
used by <ulink> to specify the URL, required
Guidelines
----------
o If you want to supply text, use <link>, else <xref>
o Do not use text with <ulink> so the URL appears in printed output
o You can supply text at the target location with 'xreflabel'
56c8d50eaf