Better build instructions

[AlexVestin]

This project currently requires ANGLE to be checked out and built in the same parent folder as this repo. is a bit confusing. Just a few lines would be very helpful.

[nkreeger]

@AlexVestin actually ANGLE is prebuilt, hosted by Google and downloaded here:

https://github.com/google/node-gles/blob/master/scripts/install.js#L76

Which platform are you using?

[AlexVestin]

I'm using Linux, is building ANGLE not required for development? That's great in that case. I downloaded and built the ANGLE project too, but I got a bit confused as to how to place the repositories in relation to each other.

[nkreeger]

No just run yarn in the project directory. It downloads and stages angle inside of /deps

[nkreeger]

I'll update dev docs soon