Permissions required not clearly documented.

[sundar-mudupalli-work]

Describe the bug
When DVT stores validation results in BigQuery or GCS or retrieves secrets using the secret manager, the permissions required by the user/service account are not clearly documented. These should be documented.

There is documentation of permissions required to store validation results in BigQuery in BigQuery connection section. DVT users don't need to set up a connection to store validation results in BigQuery. They can specify project.dataset.table. There is no documentation about permissions required for GCS and secret manager.

This detail belongs in the Running Validations section