We do not want to move POSIX utilities into subsections since they have
standard names, but we can do whatever we want with Applications :^).
This is particularly advantageous as many applications contain several
images, which declutters the man1 directory.
The URLs of the form `help://man/<section>/<page>` link to another help
page inside the help application. All previous relative page links are
replaced by this new form. This doesn't change any behavior but it looks
much nicer :^)
Note that man doesn't handle these new links, but the previous relative
links didn't work either.
