Docs: add database queries log documentation

[dilipbheda]

Fixes #5299

Description

I've updated the debugging.md file to include the env variables for enabling database queries.

Checklist

• My pull request has a descriptive title (not a vague title likeUpdate index.md).
• My pull request targets the default branch of the repository (main) or a parent feature branch.
• My commit messages follow [best practices][best_practices].
• My code follows the established code style of the repository.
• I added or updated tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no visible errors.
• I ran the DAG documentation generator (ov just catalog/generate-docs for catalog
  PRs) or the media properties generator (ov just catalog/generate-docs media-props
  for the catalog or ov just api/generate-docs for the API) where applicable.

[AetherUnbound]

Thanks for your contribution @dilipbheda! I have a suggestion that will hopefully make the documentation clearer 😄