Documentation/#1141 rtd docs intensiveday

[KathiEsterl]

Fixes #1141 .

Before merging into dev-branch, please make sure that

• the CHANGELOG.rst was updated.
• new and adjusted code is formated using black and isort.
• the Dataset-version is updated when existing datasets are adjusted.
• the branch was merged into the
  continuous-integration/run-everything-over-the-weekend-branch.
• the workflow is running successful in test mode.
• the workflow is running successful in Everything mode.

[KathiEsterl]

Eigentlich sollte das jetzt ready to merge sein :) Der Test, der failt, hat - denke ich - mit diesem Problem zu tun: #1149

@IlkaCu ?

[KathiEsterl]

GitHub actions failing for python3.7 is not a specific problem of this branch, see issue #1152