[skip ci] Update README.md

README.md

@@ -99,3 +99,7 @@ curl -X 'GET' \
   'http://localhost:8001/api/v0/projects/my_project/datasets/my_dataset/tables/apertif_table/content' \
   -H 'accept: application/json'
 ```
+
+## Contributing
+
+For developer access to this repository, please send a message on the [ESAP channel on Rocket Chat](https://chat.escape2020.de/channel/esap).