Language cleanup and a few typos

@andrewmarkle  Oh and by the way… I think that what I wrote there does not hold anymore. 

_(~> major.minor.patch)_ is for when a gem version is < 1.

When a gem reaches version 1 (and Bh just did this week), then (according to [semver.org](http://semver.org)):

> MAJOR version when you make incompatible API changes,
> MINOR version when you add functionality in a backwards-compatible manner, and
> PATCH version when you make backwards-compatible bug fixes.

That means that a user only has to indicate _(~> major.minor)_ !

For instance, when Bh 1.1 is released, it will be backwards-compatible with 1.0.

I guess this is not strictly part of your PR… so if you want to change that as well, it will be great.
Otherwise I'll just accept your change, and make a separate commit for that (since the same sentence is also repeated in a previous paragraph of the README).