README should be clear that this requires git to be on the PATH

[nickform]

It would be really great if the README made it clear that this package requires git to be on the path as well as carrying the "experimental" and "doesn't work on Windows" warnings which are shown on github. This would help make sure that devs who discover the package on www.npmjs.org are aware of these limitations before they spend time trying to try out the package.

Thanks.