docs: Clarify order of decorating class methods

[injust]

https://wrapt.readthedocs.io/en/master/decorators.html#decorating-class-methods says that wrapt decorators need to be placed outside of @classmethod decorators, but only before Python 3.9.

https://wrapt.readthedocs.io/en/master/issues.html#classmethod-get says that this also applies to Python 3.13+. Seems like the first page needs to be updated to reflect this.

This was confusing when migrating from function closure decorators using functools.wraps, as the @classmethod decorator goes on the outside in that case. So I had to swap the order of the decorators when using @function_wrapper.

[GrahamDumpleton]

Fixed in develop branch. I missed that I had not updated that parts of the docs.

Thanks.