state compatibility for theme templates better

Author: MrTango

README.rst

@@ -71,6 +71,7 @@ Compatibility
 =============
 
 Add-on's created with ``bobtemplates.plone`` are tested to work in **Plone >= 5.2** and **Python >= 3.7**.
+the only exceptions are the theming templates. Those are Plone 6 only, because the markup and Diazo rules have changed.
 
 If you need to create Plone packages for older versions of Plone and Python, please use bobtemplates.plone 5.x.
 It should work on Linux, Mac and Windows.