https://developer.github.com/v3/rate_limit/
https://developer.github.com/v3/#rate-limiting

When you have been limited, use the Retry-After response header to slow down. The value of the Retry-After header will always be an integer, representing the number of seconds you should wait before making requests again. For example, Retry-After: 30 means you should wait 30 seconds before sending more requests.