Links to outdated api documentation

Description of the issue

There are a few links in the academy that still point to the old api documentation https://oep-data-interface.readthedocs.io/en/latest/index.html. We should remove the link, only Martin has access to the Read the Docs project. I can't set up a redirect to the new page.

Ideas of solution

We now use https://openenergyplatform.github.io/oeplatform/ to develop/provide the oeplatform docs. The "work in progress" api docs are here, they will be complete by the end of september.

Workflow checklist

• I am aware of the workflow in CONTRIBUTING.md