Fix URLs.
Add 406 error.
Update Course API output with level videos.
Add Authentication & User API endpoints.
Rename Authentication to Autorization.
Document fake_release parameter for Course endpoint.
Remove reminder.
Add 400 status code for bad requests.
Fix reference to token returned from Authentication API.
Add Unprocessable Entity error.
Remove .json extensions, add args & request to Authentication API.
Indicate that Authentication API params are required.
Add new Caching section.
Add a note about 422 status codes on Auth endpoint.
Reorganize.
Rename Reset password endpoint.
Fix URL param in reset password endpoint example.
Add User Sign Up endpoint.
Add optional user sign up parameters.