DOC: reduce API docs for offset aliases
Test to see if this works with sphinx
Nice, there are some other aliases we could do the same for if this works.

Also some methods/properties that dont need to be advertised, e.g. `__call__` Yeah, first need to see if it works ;) 
(locally it did, but I would actually expect to need to edit the BDay docstring to ensure it lists no methods/attributes, similar as eg the docstring of DatetimeArray) It seems to work.

Can you say which are the aliases? Just the ones here?

https://github.com/pandas-dev/pandas/blob/5239cfa612b1798b8da46c7380c321c7e598214c/pandas/_libs/tslibs/offsets.pyx#L3487-L3494
 I think thats all of them, yes.