added co-license attribution

Hey Mark,

Any chance you would be interested in co-licensing this under MIT since it looks like it came from the work done on the [reso-odata-server](https://github.com/Retsly/reso-odata-server/blob/1bce56e99c73747b5c3a532508320c30a49c02a1/schemas/dictionary.js)? 

Normally I don't really care about licensing (as long as it's MIT) but in this case it took me like 2 days straight and the worst carpal tunnel you can imagine to type this whole thing out. At one point I actually thought I lost my entire progress with 10% left to go which was devastating (thank god for ~/.vimbackup). 

People often say that they put their blood sweat and tears into stuff, but in this case it was actually true ;) I see you already made some great updates to it by adding maxLength etc. Great stuff!

Would be awesome if you could co-attribute us on this! I'd be happy to do the same on the reso-odata-server for you / NAR if you want to include that in your PR on our repo.

Cheers, Kyle Campbell