Create Harbor Architecture Documentation

Graduated Big Bang packages require architecture documentation. Create one for Harbor in https://repo1.dso.mil/big-bang/bigbang/-/blob/master/docs/understanding-bigbang/package-architecture/

Ensure that an HA section is present, includes information that with an external DB every component can be ran with more than 1 replica. May help to review the HA document provided by upstream https://repo1.dso.mil/big-bang/apps/sandbox/harbor/-/blob/main/chart/docs/High%20Availability.md