Relay cursor based pagination in Postgres

[enisdenjo]

• https://relay.dev/docs/guides/graphql-server-specification/#connections
• https://www.graphile.org/postgraphile/connections/
• https://www.reddit.com/r/graphql/comments/uc7qrc/comment/i68x98u/?utm_source=share&utm_medium=web2x&context=3

[enisdenjo]

This can be added as a schema chapter #6.