Backport of Docs: PostgreSQL Docs added DB name note for connection_url. into release/1.11.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #16789 to be assessed for backporting due to the inclusion of the label backport/1.11.x.

The below text is copied from the body of the original PR.

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Relates to #12458 and website section: vaultproject.io/docs/secrets/databases/postgresql

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Overview of commits

• 2cc149b7d5b231c405a3b50763d9f17055cde9d9