Reformating and updating all docstrings + adding missing ones.

With the automatic creation of the reference from the docstrings we need to check them:

• check format:
  • here I already checked the format of citations
  • mainly checking the correct indentation, missing black lines, and other warnings and errors
• update information, e.g. some have more parameters then explained, or some contain outdated information or the information is too much/less detailed
• add missing ones