Document the downgrade Start up option for JIRA

Summary

JIRA 7 allows for the feature flag: jira.downgrade.allowed=true to be enabled which will give JIRA Admins the option to downgrade JIRA.

This feature is useful when a migration must occur for technical or operational reasons to an older version.

The feature is not documented and should be be included in some of the following documentation's perhaps as an include.

• Upgrading JIRA applications
• Migrating from JIRA Cloud to Server applications
• Rolling back a JIRA application upgrade

Environment

JIRA 7

Steps to Reproduce

This is a request to document a new product feature.

Expected Results

The possibility to downgrade a JIRA version should be made publicly available in the documentation.

The limitations of this feature such as how far back the instance can be downgraded to should be indicated along with providing some sample usage scenarios.

Actual Results

The flag: "jira.downgrade.allowed=true" and searching for relevant procedures does not return meaningful results.