docs: postgres 16 runs on top of noble 24.04, not jammy 22.04

[toabctl]

The text is wrong as written in this issue title. Likely a copy & paste error from the charmed-postgres 14 docs.

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Reported from: https://canonical-charmed-postgresql.readthedocs-hosted.com/16/explanation/architecture/

[syncronize-issues-to-jira]

Thank you for reporting your feedback to us!

The internal ticket has been created: https://warthogs.atlassian.net/browse/DPE-8502.

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[taurus-forever]

Assigned to the @a-velasco next sprint. Tnx for reporting!