Missing community guidelines

[Thomas Helfer]

This issue is created as part of the review of the JOSS paper (openjournals/joss-reviews#4135).

The review implies checking if proper community guidelines are present. Here are the requirements:

Community guidelines: Are there clear guidelines for third parties wishing to

1. Contribute to the software
2. Report issues or problems with the software
3. Seek support

I did not find such guidelines. You may want to have a look at this example from one of my personal projects: https://github.com/thelfer/MFrontGenericInterfaceSupport/blob/master/CONTRIBUTING.md

[Paul Stocker]

Thank you for sharing the example, I have now added the guidelines!