Updated steps for new release

doc/checklist_new_release.md

@@ -1,11 +1,12 @@
 The following steps should be performed before releasing a new storm version.
 Note that in most cases a simultaneous release of [carl](https://github.com/smtrat/carl), [storm](https://github.com/moves-rwth/storm), [pycarl](https://github.com/moves-rwth/pycarl/) and [stormpy](https://github.com/moves-rwth/stormpy/) is preferred.
 
-1. Update `CHANGELOG.md`.
-   To get all the commits from an author since the last tag execute:
+1. Update `CHANGELOG.md`:
+   * To get all the commits from an author since the last tag execute:
    ```console
    git log last_tag..HEAD --author "author_name"
    ```
+   * Set release month
 
 2. Update used carl version:
    * Update `GIT_TAG` in `resources/3rdparty/carl/CMakeLists.txt`
@@ -32,6 +33,13 @@ Note that in most cases a simultaneous release of [carl](https://github.com/smtr
 
 6. [Add new release](https://github.com/moves-rwth/storm/releases/new) in GitHub.
 
-7. Update [Homebrew formula](https://github.com/moves-rwth/homebrew-storm).
+7. Update `stable` branch:
+   ```console
+   git checkout stable
+   git merge master
+   git push origin stable
+   ```
+
+8. Update [Homebrew formula](https://github.com/moves-rwth/homebrew-storm).
 
-8. Announce new storm version on [website](http://www.stormchecker.org/news.html).
+9. Announce new storm version on [website](http://www.stormchecker.org/news.html).