comm: move help strings to markdown file

[cakebaker]

#4368 and add an "after help" text.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/misc/tee. tests/misc/tee is passing on 'main'. Maybe you have to rebase?

[tertsdiepraam]

I think we need another category apart from after help. I think the format of --help/uudoc should be something like this:

<usage>
<short summary>

<long description>

<options>

<after help>

What GNU does is that they explain some more about the options in the after help. So for instance, explaining the valid formats that an argument accepts.

I think this is what long_help in clap is for, but we weren't really using that. We could adapt the macros such that it uses the first line of the current about as short summary and the long description as the rest. For now I suppose using after help is fine though.

[cakebaker]

Hm, I'm not sure whether an additional category is needed because help_about! already supports multi-line text (for example, base32 uses it).

Clap's long_help is not helpful in this situation because it defines the long help for a single argument and not for the program, see https://docs.rs/clap/latest/clap/struct.Arg.html#method.long_help

[tertsdiepraam]

Ah got confused. I meant long_about. Nevertheless, I think you're right and we do not need anything else. I think what you wrote as after help here belongs in the about. Do you agree?

[cakebaker]

Yes, that makes sense and I fixed it in the latest push.

[tertsdiepraam]

Thanks!