Update the doc

[mposchl]

Hi, pls, update the doc, e.g. Mongo embed many works fine :) can be showstopper for someone when the doc is not up to date...

[khepin]

Hi, if you've found any out of date documentation, I'd really appreciate if you could point to it more specifically. Even better would be if you could create a pull request. Since it's for the Readme file, you can even do it all from your browser. Happy to help you go through making a pull request if you're unfamiliar with the process.