Clarify changelog for flagged features with DB changes

doc/development/changelog.md

@@ -41,7 +41,10 @@ the `author` field. GitLab team members **should not**.
   a changelog entry regardless of these guidelines if the contributor wants one.
   Example: "Fixed a typo on the search results page."
 - Any docs-only changes **should not** have a changelog entry.
-- Any change behind a feature flag **should not** have a changelog entry. The entry should be added [in the merge request removing the feature flags](feature_flags/development.md).
+- Any change behind a feature flag **should not** have a changelog entry. The
+  entry should be added [in the merge request removing the feature flags](feature_flags/development.md).
+  If the change includes a database migration, there should be a changelog entry
+  for the migration change.
 - A fix for a regression introduced and then fixed in the same release (i.e.,
   fixing a bug introduced during a monthly release candidate) **should not**
   have a changelog entry.

doc/development/feature_flags/development.md

@@ -25,7 +25,8 @@ end
 
 Features that are developed and are intended to be merged behind a feature flag
 should not include a changelog entry. The entry should be added in the merge
-request removing the feature flags.
+request removing the feature flag. If the feature contains any DB migration it
+should include a changelog entry for DB changes.
 
 In the rare case that you need the feature flag to be on automatically, use
 `default_enabled: true` when checking: