docs: Ensure table of contents covers methods of Python classes

As reported on Discord, it's difficult to scan the methods of a `DataFrame` in our docs because the table of contents only covers the top level components (i.e., the class name or top level module function name).

https://sedona.apache.org/sedonadb/latest/reference/python/#sedonadb.dataframe.DataFrame

It would be nice if we could extend the table of contents so that it includes methods (at least when that section is active), or perhaps we need to split up our docs pages so there's more than one page for all of the SedonaDB Python bindings!

Start at the linked sedonadb.dataframe.DataFrame reference page and inspect how its current table of contents is generated. Confirm the intended scope with the existing documentation structure; done means the active DataFrame section exposes its methods in the table of contents, or the page is split if that approach is chosen.

Written by the indexing model from the issue text.