Feedback: MOLT Fetch - document required permissions to add a table to a publication for Postgres

Page: https://cockroachlabs.com/docs/molt/molt-fetch.html

## What is the reason for your feedback?

[X] Missing the information I need

[ ] Too complicated

[ ] Out of date

[ ] Something is broken

[ ] Other

## Additional details

Postgres docs say

https://www.postgresql.org/docs/current/sql-createpublication.html

> To add a table to a publication, the invoking user must have ownership rights on the table. The FOR ALL TABLES and FOR TABLES IN SCHEMA clauses require the invoking user to be a superuser.

This requirement is not documented in the MOLT Fetch docs.

Otherwise the customer will get the following error:

> Error: ERROR: must be owner of table referral_pending (SQLSTATE 42501)

Jira issue: DOC-14620