Building doc pages to separate branch

[jo-mueller]

Description

This PR introduces a github action which automatically builds documentation files into a separate branch (gh-pages) and adds all doc files (.html and .doctree) to the list of ignored files. Hence, the long list of deleted files further down. Doing it this way has the big advantage that we will not have to meddle with comparing doc files in future pull requests.

I tested it on a separate fork and it works. The new workflow for PR requests would thus be:

• Make some change to the code
• Run sphinx locally to check that the documentation builds properly
• merge change to main.
• Doc files are automatically built and pushed to gh-pages, which serves as source page for biapol.github.io/biapol-utilities

I pointed to this workflow in the changed PR template and in the Contribute section on the homepage..

Let me know what you think :)

Type of change

• Bug-fix
• New feature
• Breaking change
• Documentation update

References

Fixes #29

Tests

• I adapted existing tests, because
• I added new tests to cover the code change
• All tests pass with my change

Final checks

• My change is the minimal possible work for the desired feature/fix
• I updated the documentation where necessary to cover the change
• I rebuilt the documentation page to document the change, if necessary

[jo-mueller]

The remaining conflicts come exactly from documentation files, so I would think that it makes sense to just use the changes from the incoming branch.

[haesleinhuepf]

LGTM :-)

[zoccoler]

Looks like a good idea!
I will try using this soon to add something.