DOC: add IndexSlice docstring + add to api docs

[eontwosixt]

Hello Developers,

I could not find any information about "Pandas.IndexSlice" function in API Reference.There is only one example at this link . I want to filter the pivot table as in Excel.But i am confused to using between loc(slice(...)) and IndexSlice.Please could you show some practical easy methods to filter the pivot table.

Thank you very much...

[jorisvandenbossche]

Can you give a very concrete example of a dataframe and what you want to achieve? (by the way, for usage questions, something like StackOverflow is often a easier platform to get help)
Further, everything you can do with IndexSlice, you can also do without it using a more verbose syntax (eg slice(None) instead of :).

But indeed, IndexSlice should be added to the api overview

[eontwosixt]

I had a question on this link in stackover forums.Also I want to filter the multiple index integer values .For example , on 1999 and 2000 years , A country 's Commodity - Transaction and Quantity values.