rollback-soft: T6384: tell the user to compare or commit (backport #3501)

[mergify]

Change Summary

Tell the user to compare or commit after applying the diff, since the procedure is different from the old rollback and the lack of messages may be perceived as if the rollback has already occurred.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe): behavior change.

Related Task(s)

Related PR(s)

Component(s) name

Proposed changes

How to test

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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This is an automatic backport of pull request #3501 done by [Mergify](https://mergify.com).