Update Docs to Show Latest Version

[commonsguy]

The usage notes in the project README suggests that you use 1.0.0. However 1.2.0 seems to be the latest (jitpack knows of a 1.3.0, but it's in an error state). Ideally, the docs show users the version that you want them using, and I assume that right now we should be using 1.2.0.