doc: Remove dead link to NewbieDoc Docbook Guide

The link returns 404 and no replacement is available in the project
on Sourceforge where the content once was. Since we already link to
resources for both beginner and experienced docs hackers, remove the
the dead link.

Backpatch to all supported versions as the link was added in 8.1.

Author: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Magnus Hagander <magnus@hagander.net>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reported-by: jian he <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxH=YzQPDOe+2WuYZ7seD-BOyjCBmP6JiErpoSiVZWDRnw@mail.gmail.com
Backpatch-through: 13

diff --git a/doc/src/sgml/docguide.sgml b/doc/src/sgml/docguide.sgml
index 2d8d5cd64f2bd721b31c4df48723540697710a5e..e2e2675d2c71779f776f828b3ef725ccf4b1dc3c 100644 (file)
--- a/doc/src/sgml/docguide.sgml
+++ b/doc/src/sgml/docguide.sgml
@@ -60,9 +60,7 @@
    maintained by the <ulink url="https://www.oasis-open.org">
    OASIS group</ulink>.  The <ulink url="https://www.oasis-open.org/docbook/">
    official DocBook site</ulink> has good introductory and reference documentation and
-   a complete O'Reilly book for your online reading pleasure.  The
-   <ulink url="http://newbiedoc.sourceforge.net/metadoc/docbook-guide.html">
-   NewbieDoc Docbook Guide</ulink> is very helpful for beginners.
+   a complete O'Reilly book for your online reading pleasure.
    The <ulink url="https://www.freebsd.org/docproj/">
    FreeBSD Documentation Project</ulink> also uses DocBook and has some good
    information, including a number of style guidelines that might be