Implement hook_help()

Hi;

I'm afraid this patch is far from complete. If the module is going to implement hook_help then it should yield a page that is:
a) properly formatted (wrapping a markdown file in

 tags doesn't count)
b) translatable

If you want to update the patch accordingly I'd happily merge.

I agree with leewillis77: The README.md file contains also information that is only useful before installing the module; once the module is installed, showing the README.md file is not much helpful.

Please review.

Thanks.