DOC: Deprecation Warnings in user guide

[phofl]

Location of the documentation

https://pandas.pydata.org/docs/user_guide/indexing.html#indexing-deprecate-loc-reindex-listlike

Documentation problem

We have a lot of warnings in the documentation Starting with 0.x the following is deprecated. Most of these things stopped working with 1.0. Should we update the docs and say, that this stopped working with 1.0?

[jreback]

if they are now completely working then the docs can simply be updated (eg in the case u pointed it's now an exception)