In-Org Reference App

Aura continuously builds reference docs for your app’s components, controllers etc as you are building the app! This is in addition to reference docs for pre-built Aura artifacts like Aura components, controllers, events etc.

The best part is this reference doc itself is as an Aura app and runs in your Aura enabled org!

To access it, simply go to: <yourOrg>/auradocs/reference.app.
For example: https://gs0.salesforce.com/auradocs/reference.app

Note: You can also use this to see if a particular component is supported in your org versus the open source version.