Optional user account that should be created on startup. This should be used to seed the system with an administrative account. It can be a real account (i.e. a real GitHub user) or it can be a machine account.
Providing a token is required for machine accounts, and must be 32 bytes. You can generate a random 32-byte token with the following command:
$ openssl rand -hex 16 55f24eb3d61ef6ac5e83d550178638dc