Provide new release

[markusweigelt]

• [x] adapt Readme
• [x] reset Docker image tags to latest in .env
• [x] test again thoroughly (in all host scenarios)
  • [x] MANAGED
  • [x] STANDALONE
• [x] git-tag and Docker-tag+push the module images to Dockerhub as stable
• [x] set Docker image tags to above stable versions in .env, git-commit to (new) stable branch, git-tag and make GH release
• [x] continue working on main with latest in .env (esp. by explaining how to use the stable releases)