Document that store is deprecated in favor of aggregate(local)

[krlawrence]

Starting with TinkerPop release 3.4.3.

Added aggregate(Scope,String) and deprecated store() in favor of aggregate(local).

A note should be added in the section "3.22. Using aggregate to create a temporary collection" and in the prior section where store is introduced the role of store should be better clarified

Given that aggregate(local) feels unwieldy and also confuses users, it is unlikely that store will ever be fully removed from the language.

[spmallette]

This is all changing given apache/tinkerpop#2898 so we can probably just close this one.