Not all elements that need it have @inheritdoc

Issue #329 was created because forwards seemed to be missing, but they weren't put on the element because `@inheritdoc` wasn't set. The current solution has the frontend looking for forwards on the parent classes but this should not be the final solution. Element notes suffer from the same issue.

It is expected notes & forwards are flattened onto the elements that have them without the frontend having to look for them on the parents.

Start by tracing how @inheritdoc is handled, how forwards and element notes are found on parent classes, and where the frontend consumes them. Done means notes and forwards are flattened onto the elements that own them, without frontend lookup on parent classes.

Written by the indexing model from the issue text.