Search for either rst2man or rst2man.py
Search for either rst2man or rst2man.py

Since distros differ on what name to install this as.

Fixes GH #1516

randombit/botan,randombit/botan,webmaster128/botan,webmaster128/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan