README.md enhancement

[sy2002]

Idea for enhancing the documentation in README.md:

You might want to mention in https://github.com/tuxu/ipynb-quicklook#getting-started that if the user copies to his local ~/Library/QuickLook/ instead of the global folder /Library/QuickLook, that then nothing will work.

I stumbled over this, as I normally prefer to install in my local user's folder.

[tuxu]

Thanks! You are definitely right, this should be mentioned. If you want to avoid the global installation, you can just use nbviewer-app, which ships with the QuickLook generator and should work out of the box.