Optimize state change handling.

webpages/upgrading.md

@@ -34,6 +34,10 @@ layout: vm-operator
     update the template manually. If you're using your own template, you
     have to add a virtual serial port (see the git history of the standard
     template for the required addition).
+    
+  * Stateful sets from pre 3.4.0 versions are no longer removed automatically
+    (see notes below). However, PVCs with the old naming scheme are still
+    reused.
 
 ## To version 3.4.0