Broken NewbieDoc Docbook Guide link

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/17/docguide-docbook.html
Description:

At

  https://www.postgresql.org/docs/17/docguide-docbook.html

the NewbieDoc Docbook Guide link is to

  http://newbiedoc.sourceforge.net/metadoc/docbook-guide.html

which results in an HTTP 404.

I guess the project page is

  https://sourceforge.net/projects/newbiedoc/

but it doesn't actually display the guide, so I guess one would have to
download and build it in order to read it?  Also, the project was last
updated over ten years ago (2013-04-15).  Maybe the reference to this guide
should just be removed?