https://www.freebsd.org/doc/en/books/porters-handbook/porting-submitting.html contains an obsolete URL http://www.freebsd.org/cgi/query-pr-summary.cgi?category=ports, which was 301-redirected to https://bugs.freebsd.org/bugzilla/query.cgi, which is not the list of pending port PRs but a general query page not devoted to pending ports.
Thanks for the report! I've just committed an update.
A commit references this bug: Author: jgh Date: Sat Mar 26 04:45:33 UTC 2016 New revision: 48472 URL: https://svnweb.freebsd.org/changeset/doc/48472 Log: - address old link to searching pr database New link is far too long. Link to simple search is supplied, with basic instructions to get a listing. PR: 204756 Reported by: mallocbsd@foxmail.com Changes: head/en_US.ISO8859-1/books/porters-handbook/quick-porting/chapter.xml