DOCS-12112 document views can only be created in the same database as their source collection

Author: Isabella Siu

source/core/views.txt

@@ -42,6 +42,9 @@ To create or define a view, MongoDB 3.4 introduces:
 
      db.createView(<view>, <source>, <pipeline>, <collation> )
 
+.. note::
+   You must create views in the same database as the source collection.
+
 Behavior
 --------
 

source/includes/apiargs-method-db.createView-param.yaml

@@ -15,7 +15,8 @@ description: |
   The name of the source collection or view from which to create the
   view. The name is not the full namespace of the collection or
   view; i.e. does not include the database name and implies the same
-  database as the view to create.
+  database as the view to create. You must create views in the same
+  database as the source collection.
 interface: method
 operation: db.createView
 optional: false

source/reference/method/db.createView.txt

@@ -17,7 +17,8 @@ db.createView()
    Creates a :doc:`view </core/views>` as the result of the applying
    the specified :ref:`aggregation pipeline <aggregation-pipeline>` to
    the source collection or view. Views act as read-only collections, and are
-   computed on demand during read operations. MongoDB executes read
+   computed on demand during read operations. You must create views in the same
+   database as the source collection. MongoDB executes read
    operations on views as part of the underlying aggregation pipeline.
 
    The :method:`db.createView` has the following syntax: