[bug#60003] Built docs using pandoc

[Abhishek Cherath]

Hello!

So I somehow missed this patch, and wrote my own here:
https://issues.guix.gnu.org/70082

I've used git-fetch, and built the man pages etc

There's a bunch of tests that don't pass though, as I recall most were
some serialization thing.

I've not seen any impact on operation yet, however.

Sincerely,
Abhishek Cherath.