Add deprecations to update docs for 6.0

doc/update/5.4-to-6.0.md

 # From 5.4 to 6.0
 
+### Deprecations
+
+#### Global projects
+
+We Derecated root(global) namespace for projects. 
+So you need to move all your global projects under group/users manually before update or it will be moved automatically to owner namespace during update.
+
+#### 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.
+
+
 ### 0. Backup
 
 It's useful to make a backup just in case things go south: