DOCS-153 add note about all config servers needing to be up on initial setup

also fix error (elided sentence) introduced in fc3b14f

Author: Ed Costello

source/administration/sharding.txt

@@ -59,6 +59,10 @@ more detail or use the following procedure as a quick starting point:
    :doc:`command line </reference/mongod>` and :doc:`configuration
    file </reference/configuration-options>` options are available for config
    server instances.
+   
+.. note::
+
+   All config servers must be running when you first set up a shard cluster.
 
 #. Start a :program:`mongos` instance issuing the following command:
 
@@ -889,8 +893,10 @@ For redundancy, all production :term:`shard clusters <shard cluster>` should
 deploy three config servers processes on three different machines.
 
 Do not use only a single config server for production deployments.
-Consider deploying a single config server for testing.
-immediately. The following process shows how to upgrade from one to
+Consider deploying a single config server only for testing.
+You should upgrade to three config servers immediately if you are
+shifting to production.
+The following process shows how to upgrade from one to
 three config servers.
 
 #. Shut down all existing MongoDB processes. This includes: