Improve readme and contributing documentation.

Closes #76 (closed)

added Kriton track discussion improvement split statusto do labels

assigned to @hannes.mayr

requested review from @manuela.richter

merged

mentioned in commit 91914435

@hannes.mayr @m.hock : Pipeline passed with warnings. Should we investigate this warning?

No, its fine. That's work in progress of #31 (closed) .