Readme: checkout language

[skvale]

The readme says

.checkout(options) - uses the checks out the supplied options object/array to check out.

git-js/simple-git/readme.md

Line 239 in 459ec92

- `.checkout(options)` - uses the checks out the supplied [options](#how-to-specify-options) object/array to check out.

That wording feels a bit off, how about:

.checkout(options) - check out a tag or revision using the supplied name or [options](https://github.com/steveukx/git-js#how-to-specify-options)

[steveukx]

Thanks for the suggestion, this will be released with the next version.