Add document how to find mysql backup file and print path in output

[jneo8]

• Print backup file path on output
• Refactor how-to backup document, add information where to find the file.

[samuelallan72]

@jneo8 is this addressing #492 ?

[samuelallan72]

Thanks!

[chanchiwai-ray]

Please check the output document: https://canonical-charmed-openstack-upgrader--589.com.readthedocs.build/en/589/how-to/backup/

[rgildein]

Title of this is "docs: Add document how to find mysql backup file" and you are changing also the code. Can you align it and provide output example? Thanks

[jneo8]

Title of this is "docs: Add document how to find mysql backup file" and you are changing also the code. Can you align it and provide output example? Thanks

Updated

[samuelallan72]

Thanks, for making the changes, I think that makes it clearer for future readers. :)