Fix the edit link for API documentation
The swh-docs building process symlinks the documentation for
individual modules into the swh-docs tree to generate a single Sphinx
project. The “Edit this page” link therefore needs to point to the right
repository on GitLab in these case.
We try to implement this using the edit_page_url_template option
of the PyData theme, see: https://pydata-sphinx-theme.readthedocs.io/en/stable/user_guide/source-buttons.html#custom-edit-url
We can take advantage that it’s a Jinja2 template to recognize
that API documentation file path starts with devel/swh- and adjust
accordingly. This is a bit of a hack, but we can hope it’ll be enough as
long as we stay consistent.
- Closes: #4735 (closed)