Move documentation of Python from documentation repo to ResInsight repo

[magnesj]

Background

The source code for the Python documentation is located at https://github.com/OPM/ResInsight-UserDocumentation/tree/next-major-release/docs
This repo is used by ReadTheDocs to produce the documentation on https://api.resinsight.org/en/main/
A workflow copies the latest successful build from ResInsight to the documentation site https://github.com/OPM/ResInsight-UserDocumentation/blob/next-major-release/.github/workflows/update-from-latest.yml

NB Technical challenge

Sphinx is used to generated the Python documentation. The rips Python library is a bit special as it is generated partly from Python source code and partly generated Python code based on code in C++ in ResInsight.

Investigate how to move the documentation source code for Sphinx to ResInsight.