Refresh Tokens

[arosenb2]

As part of token generation, it could be useful to allow the creation of a refresh_token (RFC 6749 §1.5) instead of the default long-lived access tokens.

Apologies if this is already an included capability; I wasn't able to make the determination in the documentation. If the recommended behavior is to manually create a second token to use as a refresh token, it could be helpful to include documentation specifying that.