DOCSP-14128: Adds note calling out that you can't assign a db user to more than on… (#769)

* Adds note calling out that you can't assign a db user to more than one resource

* move note location

* Fixes important tag spacing, clarifies what a resource is (still need to double check that w a tech reviewer)

* adds space

* Updates note w info about admin users. I'd like to claridy this in tech review

Author: mongodbchez

source/tutorial/manage-database-users-scram.txt

@@ -73,6 +73,18 @@ Before managing database users, you must deploy a
 Add a Database User
 -------------------
 
+.. important:: 
+  
+   You cannot assign the same database user 
+   to more than one MongoDB
+   :doc:`standalone </tutorial/deploy-standalone>`,
+   :doc:`replica set </tutorial/deploy-replica-set>`, or
+   :doc:`sharded cluster </tutorial/deploy-sharded-cluster>`.
+   This includes database users with 
+   :guilabel:`admin` roles.
+
+
+
 Create User Secret
 ~~~~~~~~~~~~~~~~~~