Our [[ https://archive.softwareheritage.org/api/ | API doc page ]] only lists endpoints, we need to complement those with a general description of the API, possibly terminology, etc.
There are various possibilities to achieve that:
1. rely on the global docstring of the .py file that already contains the docstring for the varions endpoints
2. just use the Flask HTML template of the /api/ endpoint
3. rely on a static file (e.g. header.html) that is deployed locally and loaded dynamically by the page template
(3) is probably the easier to code, and it will also allow to easily have an equivalent footer.html, and other static pages for other parts of the webapp in the future.