DTSPO-18332 - Rename aso postgres server script and update documentation

[louisehuyton]

Jira link

DTSPO-18332

Change description

• Rename postgres-setup.sh to 'add-postgres-server.sh'
• Update references to script ^^
• Include example output from script in documentation

Testing done

N/A

Checklist

• commit messages are meaningful and follow good commit message guidelines
• README and other documentation has been updated / added (if needed)
• tests have been updated / new tests has been added (if needed)
• Does this PR introduce a breaking change

🤖AEP PR SUMMARY🤖

Docs/aso-setup-v2.md

• Updated the documentation to mention running add-postgres-server.sh instead of postgres-setup.sh for setting up the Postgres server.
• Added a note to refer to a PR for expected output of the script.

bin/v2/postgres-setup.sh

• File renamed from postgres-setup.sh to add-postgres-server.sh.
• Updated the usage function to reflect the new filename add-postgres-server.sh.