AWS PostgreSQL guides for Fastah IP geolocation

New guides: Amazon RDS for PostgreSQL | Amazon Aurora PostgreSQL and DSQL

We added AWS PostgreSQL deployment guides that show how to store Fastah IP geolocation responses using native data types and extensions.

• Compare Amazon Aurora PostgreSQL and Aurora DSQL for Fastah workloads, including support for inet, cidr, PostGIS, and timezone-aware timestamps.
• Follow copy-pasteable SQL examples to model and index IP addresses and subnets using inet/cidr and GiST indexes.
• Enable PostGIS on supported AWS PostgreSQL engines and store locationData coordinates as SRID 4326 geometry points.
• Store timezone-aware timestamps using TIMESTAMPTZ together with Fastah's locationData.tz value.