Update source/reference/command/enableSharding.txt

Pretty sure the description here is wrong - need to provide the database name to enableSharding (it's an admin command that gets run against the admin database).

Author: Greg Studer

source/reference/command/enableSharding.txt

@@ -11,7 +11,7 @@ enableSharding
 
    .. code-block:: javascript
 
-      { enableSharding: 1 }
+      { enableSharding: "<database name>" }
 
    Once you've enabled sharding in a database, you can use the :dbcommand:`shardCollection`
    command to begin the process of distributing data among the shards.