Update guide - DB migration with fallback steps and more error log example.

[rajlearner17]

Guide to be updated
https://turbot.com/guardrails/docs/guides/hosting-guardrails/disaster-recovery/database-upgrade#monitor-1

Reason for update
Explain why this guide needs to be updated (e.g., outdated information, missing content, unclear explanations).

• Add the fallback (revert) steps if the installation will stop proceeding at end of the step10.
• Add h3 section under step 10.
• Add the more error log (which can be ignored in restore process)example as we got in live migration.

Proposed changes
Describe the specific changes or additions you're suggesting for the guide. Be as detailed as possible.