Make description technically correct for both visitors and developers

Author: stevepiercy

docs/backend/upgrading/version-specific-migration/upgrade-to-61.md

@@ -92,7 +92,7 @@ The goal of turning more of the current core packages into core add-ons is to ma
 
 ## Discussion is disabled by default
 
-Discussion, a feature that allows visitors to your site to comment on pages, is disabled by default in Plone 6.1 and later.
+Discussion, a feature that allows visitors to your site to comment on web pages for any content type, is disabled by default in Plone 6.1 and later.
 To enable discussion, you need to perform the following tasks.
 
 % Please add sufficient details for how to do this task, then delete this comment.