Create CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,11 @@
+# How to Contribute to this Repository
+
+Before contributing to this specific repository, please read the [Contribution Guidelines](https://nrkno.github.io/sofie-core/docs/for-developers/contribution-guidelines) for the _Sofie_ project.
+
+
+## Branches
+This repository uses the following branches:
+
+* **_master_** is our main branch. We consider it stable and it is used in production.
+
+We encourage you to base your contributions on the latest **master** branch of this repository. The [_Sofie Releases_](https://nrkno.github.io/sofie-core/releases) page collects the status and timeline of the _Sofie_ releases.