Somehow fix haddocks for the typeclass

[mgsloan]

The current haddocks for the Store class are pretty awful - https://www.stackage.org/haddock/lts-9.0/store-0.4.3.1/Data-Store.html#t:Store

The issue is mostly due to haddock itself, for some bizarre reason it is not listing all the instances. Beyond that, it is also duplicating the documentation for the methods twice.

This is particularly problematic for Store because it generates many instances. These haddocks make it seem like it has few.