Add Ember CLI Api docs

Didn't see anything filed already for this, so kicking this off.

I looked into how this repo works to see if I could port over https://ember-cli.com/api/, but looks like it's making a request to api-store.emberjs.com, which points to AWS. I'm assuming some script/job is building and posting docs at release time to AWS, and the same needs to happen for Ember CLI. Will post more of my findings here as I discover how it works. If there's any existing work for this, let me know!