Initial commit of Rec Room docs in Markdown format

[rorito]

• Will eventually move docs to MDN App Center - Quick Start, but
  we need them on GitHub as well.

[brittanydionigi]

Might want to link to a good write-up explaining MVC architecture? Would be useful for beginner developers who haven't heard of the concept, and not wildly obtrusive for users that are already familiar.

[rorito]

I'm thinking Appendix 2 will contain that. In the google docs I copied and pasted chunks that are important concepts from the Ember guides, but it needs to be re-written.

[rorito]

Here's my suggested change:

Rec Room uses Ember.js as the framework to build your app’s controllers, models, and views. While you don’t need to know Ember.js (our documentation will walk you through the basics you’ll need), some previous knowledge would be useful. You can always refer to the excellent Ember.js guides. They do a good job explaining the structure of Ember apps, especially in relation to the MVC (Model View Controller) design pattern.

We also provide a brief introduction to important Ember concepts in [Appendix 2: A Brief Introduction to Ember](A2 - A Brief Introduction to Ember.md).

[brittanydionigi]

Feels a little odd to be throwing around info and links about Hosted/Privileged/Packaged Apps in this paragraph before the section explaining that there are different types of applications. Not sure how to re-word/organize this yet but will come back to this and PR something.

[rorito]

Good point, I put Types of Applications before the Manifest File section

[tofumatt]

localForage 1.0 annoying switched to an error-first style callback, so this should actually be: localforage.getItem('key', function(err, value) {