[Feature request] List class method in right menu

When generating documentation for a class, it would be good to be able to list on the right menu all of its methods.

For context, in `huggingface_hub` we have a class `HfApi` with a lot of methods (~30). My problem with [the generated documentation](https://huggingface.co/docs/huggingface_hub/main/en/package_reference/hf_api#huggingface_hub.HfApi) is that to find the documentation of a specific method, I either need to Ctrl+F (so I need to know the name) or to scroll over the entire page and hope to see it. I think that some users might be missing documentation because of that. A manual solution is to write a subheader (###) for each method but if it can be just an option to add to the autodoc, that would be perfect :pray: