Merge branch 'docs/update-maintainer-guide' into 'main'

Update maintainer documentation

See merge request !866

docs/maintainers/README.md

@@ -93,7 +93,7 @@ about to be released is ready:
   ```
 - Ensure that all tests still pass
   ```shell
-  source .venv/bin/activate
+  source .venv_[OS_CODENAME]/bin/activate
   pytest tests
   ```
 - Trigger release
@@ -114,6 +114,9 @@ about to be released is ready:
     - Type "yes" to automatically create the commits and push
   - Wait for Axii to perform the release and for all pipelines to pass
 - After the release
+  - Close the [corresponding milestone](https://git.h2t.iar.kit.edu/sw/armarx/meta/axii/-/milestones)
+  - Rename "Next Release" to the next planned version number
+  - Create a new milestone "Next Release"
   - Axii provides you a suggestion for a message to announce the release.
     Feel free to distribute it via suitable channels, in case of important
     features or breaking changes.