Hook for modifying method signatures

[jacobtomlinson]

Thanks for this plugin, it's really great!

I have a package which uses a class decorator to modify some methods of a class. Specifically it wraps coroutines in a sync wrapper.

When documenting with sphinx-autoapi the methods still show as async despite being replaced by a sync method by the decorator. I don't expect the parser to handle this, it's definitely an edge case, but I wondered if there was an event I could hook so I can write a plugin to fix this on my end?