The dashboard's Sync: the current repository list, plus a GitHub re-read.

Returns exactly what GET /repos returns (under repositories), and -- at most once per install per minute -- starts a background re-read of the tenant's GitHub installs so repos created or granted on GitHub since the last read show up. The re-read is additive (new repos land disabled; nothing is ever disabled), so any member who can list repositories may trigger it. githubSync.started tells the client whether to re-poll shortly; retryAfterSeconds when throttled.