Add README.md

README.md

+# Parallel programming with MPI
+
+This repository contains various exercises and examples on parallel programming with message passing interface (MPI).
+
+A working MPI installation is needed, please see individual exercise/example for detailed build instructions.
+
+## How to contribute
+
+Any contributions (new exercises and examples, bug fixes, improvements etc.) are
+warmly welcome. In order to contribute, please follow the standard
+Gitlab workflow:
+
+1. Fork the project into your personal space
+2. Create a feature branch
+3. Work on your contributions
+4. Push the commit(s) to your fork
+5. Submit a merge request to the master branch
+
+As a quality assurance, the merge request is reviewed by PRACE staff before it is accepted into main branch.