added my workflow-paper as CONTRIBUTING page
I cleaned up the language of my mailed paper and addded
- two cases of troubleshooting
- information about the changes in the workflow when you become member of the group (there is more to be written!)
- a hint to the preface that this is a description for beginners and where experts can find straight forward help and
- some informations about the group I took from other pages (mainly in the wiki)
Klaumi