These files all have options that trip up the `nix-doc-munge`
conversion tool for one reason or another (syntax that clashes with
Markdown, options that were already using Markdown syntax despite not
being marked that way, output that differs slightly after conversion,
syntax too elaborate to convert with some cheap regular expressions,
...). Translate them manually and do a little copyediting to options
in the vicinity while we're at it.
Starting with state version 22.11 we completely reset the PATH
variable in the activation script. This is to avoid impurities and
unexpected results if the activation script accidentally uses a
command found in the user's PATH.
