DOCS-401: minor edits

Author: Sam Kleinman

source/administration/replica-sets.txt

@@ -941,26 +941,27 @@ scan and pull the entire oplog into memory.
 Duplicate Key Error on local.slaves
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The *duplicate key on local.slaves* error, shown below, occurs when a
+The *duplicate key on local.slaves* error, occurs when a
 :term:`secondary` or :term:`slave` changes its hostname and the
 :term:`primary` or :term:`master` tries to update its ``local.slaves``
 collection with the new name. The update fails because it contains the
-same `_id` value as the document containing the previous hostname.
+same `_id` value as the document containing the previous hostname. The
+error itself will resemble the following.
 
-.. example::
-
-   .. code-block:: javascript
+.. code-block:: none
 
-      exception 11000 E11000 duplicate key error index: local.slaves.$_id_  dup key: { : ObjectId('<object ID>') } 0ms 
+   exception 11000 E11000 duplicate key error index: local.slaves.$_id_  dup key: { : ObjectId('<object ID>') } 0ms 
 
-This is a benign error and does not affect replication operations on
+This is benign error and does not affect replication operations on
 the :term:`secondary` or :term:`slave`.
 
-To stop the error from appearing, drop the ``local.slaves`` collection
-from the :term:`primary` or :term:`master`, as shown here:
+To prevent the error from appearing, drop the ``local.slaves``
+collection from the :term:`primary` or :term:`master`, with the
+following sequence of operations in the :program:`mongo` shell:
 
 .. code-block:: javascript
 
+   use local
    db.slaves.drop()
 
 The next time a :term:`secondary` or :term:`slave` polls the