Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -6,6 +6,9 @@ Before contributing to this specific repository, please read the [Contribution G
 ## Branches
 This repository uses the following branches:
 
-* **_master_** is our main branch. We consider it stable and it is used in production.
+* **_master_** is our main branch. We consider it stable and it is used in production. It is intended to be compatible with the stable release of Sofie Core.
+* **_develop_** is our in-development branch. It is intended to be comatible with the latest in-development (unstable) release of Sofie.
 
-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.
+We encourage you to base your contributions on the **_master_** branch of this repository by default, unless your contribution depends on a new / unstable feature of Sofie Core, then base on **_develop_**.
+
+The [_Sofie Releases_](https://nrkno.github.io/sofie-core/releases) page collects the status and timeline of the _Sofie_ releases.