Warn about the container-handle-image-data command in the changelog

Author: dralley

CHANGES.md

@@ -163,7 +163,6 @@ No significant changes.
 
 #### Misc {: #2.27.0-misc }
 
-- 
 
 ---
 
@@ -292,6 +291,8 @@ No significant changes.
 
 ## 2.26.0 (2025-08-14) {: #2.26.0 }
 
+**WARNING:** If your installation pre-dates pulp_container 2.20, make sure that you run `pulpcore-manager container-handle-image-data` before upgrading to (or past) this release. If your installation began after pulp_container 2.20, or if you have already run this command at some point, this is not necessary.
+
 #### Features {: #2.26.0-feature }
 
 - Bump pulpcore upperbound to <3.100. pulp_container is now a Python >=3.11 project.
@@ -329,6 +330,8 @@ No significant changes.
 
 ## 2.25.0 (2025-04-15) {: #2.25.0 }
 
+**WARNING:** If your installation pre-dates pulp_container 2.20, make sure that you run `pulpcore-manager container-handle-image-data` before upgrading to (or past) this release. If your installation began after pulp_container 2.20, or if you have already run this command at some point, this is not necessary.
+
 #### Features {: #2.25.0-feature }
 
 - Added full support for domains.
@@ -777,7 +780,7 @@ No significant changes.
 
 ### Misc
 
--   
+-
 
 ---