Documentation should have some canonical values #27

I'm building some wrappers that'll use CityHash32 and CityHash64 under the hood. It'd be helpful for building tests that my wrappers are correct (e.g. pass the right offsets down) if the README.md has some canonical values for the current version, i.e. just

CityHash32("") = ...
CityHash32("some value") = ...

and same for 64.

Obviously these are unstable and could change, but it'd still be highly helpful. Thanks!