Document basic resource registration (STAC metadata ingestion)

[j08lue]

When deploying eoapi-k8s out of the box, what mechanisms do users have available to load data into pgSTAC?

This was recently discussed here:

• What is the best way to populate the PgStac on eoapi-k8s? #73

And we would like to add/reference docs on this in the EOEPCA+ building block documentation:

• Document basic resource registration (STAC metadata ingestion) with pypgstac EOEPCA/resource-discovery#96

Acceptance criteria

• Docs exist, either in EOEPCA+ or in this repo, on how to do basic ingests with out-of-the-box eoapi-k8s