Document how to enable sql debug in pulp logs

[pedro-psb]

Request

As an admin (and developer),
I want to have a reference snippet on how to enable SQL debugging in the pulp logs,
so I can troubleshoot the relation between API calls and database activity.

Context

This was asked in pulp internal channels, and I personally think this would be helpful too.

Probably a section to be added here:
https://pulpproject.org/pulpcore/docs/admin/guides/troubleshooting/