DOCSP-19786 clarify wording in warning (#101)

Author: Dave

source/reference/method/db.collection.validate.txt

@@ -96,11 +96,24 @@ finishes.
 
 .. warning::
 
-   Due to the performance impact of validation, consider running
-   :method:`db.collection.validate()` only on :term:`secondary` replica
-   set nodes. You can use :method:`rs.stepDown()` to instruct the
-   current :term:`primary` node to become a secondary to avoid
-   impacting a live primary node.
+   Validation has exclusive lock requirements that affect performance.
+   Consider only running :method:`db.collection.validate()` on nodes
+   that are not servicing reads and writes.
+
+   To isolate the impact of the validation operation from client
+   applications, run :method:`db.collection.validate()` on a secondary
+   node.
+
+   :ref:`Convert a secondary node
+   <configure-hidden-replica-set-member>` into a replica set
+   :ref:`hidden member <replica-set-hidden-members>` and use the hidden
+   node to further isolate the :method:`db.collection.validate()`
+   operation.
+
+   .. tip:: 
+
+      Convert the current primary node to a secondary node with
+      :method:`rs.stepDown()`. 
 
 Data Throughput Metrics
 ~~~~~~~~~~~~~~~~~~~~~~~

source/tutorial/configure-a-hidden-replica-set-member.txt

@@ -47,6 +47,7 @@ set its :rsconf:`members[n].hidden` value to
      "hidden" : true
    }
 
+.. _configure-hidden-replica-set-member:
 
 Configuration Procedure
 ~~~~~~~~~~~~~~~~~~~~~~~