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.
Chroot exists neither in code nor in documentation. If we add-in the
feature again, it will be simple enough to add it back in to the
documentation. For now, let's clean it up, instead of refering to things
that don't exist.
Found by markdown-checker.
When mounting an Ext2FS, a block device source is required. All other
filesystem types are unaffected, as most of them ignore the source file
descriptor anyway.
Fixes#5153.
