Documentation update assign cts to buildings

[nailend]

Fixes #671

This branch was already merge before in #826 which induced some problems #950.

This is just some documentation update

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.