Bug#995442: improve README.md on salsa repo

[c.buhtz at posteo.jp]

Package: python-debian
Version: 0.1.41

This is about the salsa repository for this package.
https://salsa.debian.org/python-debian-team/python-debian

Issues are deactivated in that repo on salsa.

For new users (e.g. Me, who tries to dive deeper into python debian 
packaging) it is unclear what this package is for.
I would recommend to improve the README.md (e.g. with examples) to give 
a better understanding what it does.

The link to the "API documentation" in the README.md is dead. So I am 
not able to dive deeper into documentation.

Kind
Christian Buhtz