API doc: endpoint index should list only the first paragraph of method docstrings
For instance, at https://archive.softwareheritage.org/api/1/ , the entry for /api/1/directory/ should read "Get information about directory or directory entry objects.", excluding subsequent paragraphs. On the other hand, the entire docstring should be shown when visiting https://archive.softwareheritage.org/api/1/directory/ (this part is unchanged w.r.t. what is shown now).
Migrated from T663 (view on Phabricator)