docs: add shield and support section to readme

README.md

@@ -11,6 +11,7 @@ SPDX-License-Identifier: CC-BY-4.0
 [![Zenodo PyPSA-Eur-Sec](https://zenodo.org/badge/DOI/10.5281/zenodo.3938042.svg)](https://doi.org/10.5281/zenodo.3938042)
 [![Snakemake](https://img.shields.io/badge/snakemake-≥5.0.0-brightgreen.svg?style=flat)](https://snakemake.readthedocs.io)
 [![REUSE status](https://api.reuse.software/badge/github.com/pypsa/pypsa-eur)](https://api.reuse.software/info/github.com/pypsa/pypsa-eur)
+[![Stack Exchange questions](https://img.shields.io/stackexchange/stackoverflow/t/pypsa)](https://stackoverflow.com/questions/tagged/pypsa)
 
 # PyPSA-Eur: A Sector-Coupled Open Optimisation Model of the European Energy System
 
@@ -90,6 +91,14 @@ to 50-200 nodes.
 
 Already-built versions of the model can be found in the accompanying [Zenodo
 repository](https://doi.org/10.5281/zenodo.3601881).
+
+# Contributing and Support
+We strongly welcome anyone interested in contributing to this project. If you have any ideas, suggestions or encounter problems, feel invited to file issues or make pull requests on GitHub.
+-   In case of code-related **questions**, please post on [stack overflow](https://stackoverflow.com/questions/tagged/pypsa).
+-   For non-programming related and more general questions please refer to the [mailing list](https://groups.google.com/group/pypsa).
+-   To **discuss** with other PyPSA users, organise projects, share news, and get in touch with the community you can use the [discord server](https://discord.gg/JTdvaEBb).
+-   For **bugs and feature requests**, please use the [PyPSA-Eur Github Issues page](https://github.com/PyPSA/pypsa-eur/issues).
+
 # Licence
 
 The code in PyPSA-Eur is released as free software under the