DOCS-465: adding replication authentication issue

Author: Sam Kleinman

source/release-notes/2.2.txt

@@ -51,12 +51,18 @@ Upgrading a Standalone ``mongod``
 Upgrading a Replica Set
 ~~~~~~~~~~~~~~~~~~~~~~~
 
-While you may upgrade your replica set in any order, to minimize
-downtime, use the following procedure:
+If your replica set runs with authentication (i.e. with
+:option:`--keyFile <mongod --keyFile>`,) you *must* upgrade all
+members of the set at once. When using authentication 2.2 members
+cannot interact with 2.0 members.
+
+If your replica set does *not* use authentication you may upgrade your
+replica set in any order, to minimize downtime, use the following
+procedure:
 
 #. Upgrade the :term:`secondary` members of the set one at a time by
-   shutting down the :program:`mongod` and replacing the binary with
-   the 2.2 binary.
+   shutting down the :program:`mongod` and replacing the 2.0 binary
+   with the 2.2 binary.
 
 #. Use the :method:`rs.stepDown()` to step down the primary to allow
    the normal :ref:`failover <replica-set-failover>` procedure.
@@ -400,7 +406,7 @@ information.
 
 MongoDB extended JSON now includes a new ``Timestamp()`` type to
 represent the Timestamp type that MongoDB uses for timestamps in the
-oplog among other contexts.
+:term:`oplog` among other contexts.
 
 This permits tools like :program:`mongooplog` and :program:`mongodump`
 to query for specific timestamps. Consider the following