DOCS-15427 System Collection Limitations (#59)

* DOCS-15427 Adds System Collection limitation

* DOCS-15427 Adds System Collection limitation

* DOCS-15427 Fixes per Joe

* DOCS-15427 Fixes per Joe

Author: kennethdyer

source/reference/limitations.txt

@@ -107,9 +107,36 @@ Multiple Clusters
 - Syncing one source cluster to many destination clusters is not
   supported.
 
+System Collections
+------------------
+
+{+c2c-product-name+} does not replicate :ref:`system collections 
+<metadata-system-collections>` to the destination cluster.
+
+If you issue a :dbcommand:`dropDatabase` command on the source cluster,
+this change is not directly applied on the destination cluster. Instead,
+{+c2c-product-name+} drops user collections and views in the database 
+on the destination cluster, but it does not drop system collections 
+on that database.
+
+For example, on the destination cluster:
+
+- The drop operation does not affect a user-created  
+  :data:`system.js <<database>.system.js>` collection. 
+
+- If you enable profiling, the :data:`system.profile 
+  <<database>.system.profile>` collection remains.
+
+- If you create views on the source cluster and then drop the database,
+  replicating the drop removes the views, but leaves an empty
+  :data:`system.views <<database>.system.views>` collection.
+
+In these cases, the replication of ``dropDatabase`` removes all user-created
+collections from the database, but leaves its system collections on the
+destination cluster.
 
 .. contents:: On this page
    :local:
    :backlinks: none
    :depth: 1
-   :class: singlecol
+   :class: singlecol