REAMDE.rst could need some love

[sbuerk]

A README.md, REAMDE.rst or similar is the first
place contributors would look into for some kind of
intstruction on how to contribute workflow is is or
how to execute the several tools.

For that, maybe we should donate some love to the
README.rst for:

• explain what this package is for/what it does
• explain shortly prefered contribution steps
• explain Build/Scripts/runTests.sh for CI and local usage
• add build badge(s) from the job executions