Most of these sites support HTTPS (some forward to HTTPS when accessing
the HTTP versions). Use HTTPS directly if supported.

Some URLs led to 404 error pages. Adjusted the links to point to
new locations.

I did not adjust the Microsoft HTML Help Workshop link because it seems
that this software is not available anymore. Instead of removing the
link entirely I kept it there in case it helps someone to find the
software on archived websites.

Mostly found with codespell and during code review.

Update the docs to mark all members of those structures deprecated, and
 suggest what to use instead.

Whilst working on the Reproducible Builds effort [0] I noticed that
json-c could not be built reproducibly.

This is because it used the full, absolute path name as an (sanitised)
input to a filename, resulting in some binary package containing, for
example:

  /usr/share/doc/libjson-c-dev/html/md__build_1st_json-c-0_815_issues_closed_for_0_813.html
                                        ^^^^^^^^^^^^^^^^^^^^^^
or

  /usr/share/doc/libjson-c-dev/html/md__build_2_json-c-0_815_2nd_issues_closed_for_0_813.html
                                        ^^^^^^^^^^^^^^^^^^^^^^^^

These differing values are based on the path in which json-c is built. This was
originally filed in Debian as #966657 [1].

 [0] https://reproducible-builds.org/
 [1] https://bugs.debian.org/966657