A patch to the script that generates the man page adding such a URL would be accepted. The existence of the non-free tar doc package might also deserve passing mention...
[email protected] wrote: >X-debbugs-Cc: [email protected] >Package: tar >Version: 1.26+dfsg-6 >File: /usr/share/man/man1/tar.1.gz > >BUGS > The GNU folks, in general, abhor man pages, and create info documents > instead. Unfortunately, the info document describing tar is licensed > under the GFDL with invariant cover texts, which makes it impossible to > include any text from that document in this man page. Most of the text > in this document was automatically extracted from the usage text in the > source. It may not completely describe all features of the program. > > May 31, 2013 > >So please say what URL to click on to see it, like man cpio now says!

