Add the contribution.md to the README.md
This short entry can be mentioned in the README.md. Need not be an extra file.
The Helmholtz Codebase and Mattermost will not be available between May 2nd, 16:15 and May 2nd, 17:45. In preparation of the GitLab major upgrade 17.0 a database maintenance is required.
Please subscribe to service-announcement@hifis.net if you would like to receive regular information on HIFIS service annoncements via email.
This short entry can be mentioned in the README.md. Need not be an extra file.