Better cues for naming convention override in source vs. global config

Product enhancements to provide better cues to users for the naming convention config precedence specified in the green box at the end of this section: https://hasura.io/docs/latest/schema/postgres/naming-convention/#pg-source-naming-convention

Start with the naming convention documentation section linked in the issue, especially the green-box explanation of source versus global configuration precedence. Identify the specific user cues expected for that precedence; the work is done when users can understand which configuration takes priority without relying on unstated context.

Written by the indexing model from the issue text.