Document Harper's ability to auto-incrementing ids

[kylebernhardy]

The agent has a good understanding of Harper's ability to create auto-generated UUID values, but is unaware that Harper can do auto-incrementing numeric ids. The numeric incrementing ids are more performant and storage sensitive than UUIDs and would be best practice.
For reference:
https://docs.harperdb.io/release-notes/v4-tucker/4.4.0#auto-incrementing-primary-keys
https://docs.harperdb.io/docs/4.6/developers/applications/defining-schemas#primarykey