Better description based on a conversation in the contributor room.

doc/update/5.4-to-6.0.md

@@ -9,9 +9,13 @@ So you need to move all your global projects under group/users manually before u
 
 #### Teams
 
-We drop teams support as separate entity for 6.0 in favor of group membership.
-So now you will be able to manage group members in order to provide access to corresponding projects.
-
+We deprecate teams as separate entity in 6.0 in favor of group membership.
+The old combination of groups and teams was confusing for a lot of people.
+And when the members of a team where changed this wasn't reflected in the project permissions.
+In GitLab 6.0 you will be able to add members to a group with a permission level for each member.
+These group members will have access to the projects in that group.
+Any changes to group members will immediately be reflected in the project permissions.
+You can even have multiple owners for a group, greatly simplifying administration.
 
 ### 0. Backup
 
@@ -81,4 +85,4 @@ To make sure you didn't miss anything run a more thorough check with:
 
     sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
 
-If all items are green, then congratulations upgrade complete!
+If all items are green, then congratulations upgrade complete!
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