Simple as it is, where is the documentation and the API documentation? Is it available online?
Edit: as of April 2023, the doc has been reinstated and and can be found at the expected place.
If it disappears again, it can still be found on the Internet Archive.
Note for future viewers: this is the doc for Gimp-2.x/Python-2.7, not for Gimp-3.x/Python-3.x.