How-to-contribute-to-using-gitlab.md

@@ -6,7 +6,7 @@
  - When you need to update your branch because of other parallel developments, read [Info on git rebase vs. git merge](Info-on-git-rebase-vs.-git-merge)
  - Make sure the CI with all unit tests for your branch are working
  - Follow the coding guidelines
- - Use `do-clang-format.py --apply` 
+ - Use `do-clang-format.py --apply`, if there are problems with the clang-version, do `do-clang-format.py --apply --docker` (requires docker to be installed). 
  - Use `do-copyright.py --check` and `do-copyright.py --year 202x`
  - When development is complete
    - remove WIP status