Add extra detail

Include note that keys must be enclosed in quotes - quite important and can trip some people up.

Also some information about the comma-first style.
I personally feel instead of using ```(' or \")``` say "enclosed in single or double quotes". Having the \" would confuse a beginner I feel even though that is really meant to not break the json. 

But then again, maybe it would be a good idea to have it but have a note somewhere saying if someone wants to use a double quote inside of a string, they just use a ```\``` forward slash character to do so.