Add sumaries of Okapi and Auth operations
Add sumaries of Okapi and Auth operations

Also remove last mentions of the API keys, and explain the trickery in
the early prose.

julianladisch/okapi-acquisitions-poc,funkymalc/okapi,folio-org/okapi,funkymalc/okapi,folio-org/okapi,julianladisch/okapi-acquisitions-poc,julianladisch/okapi-acquisitions-poc