DOCS-268: minor edits

Author: Sam Kleinman

source/administration/replica-sets.txt

@@ -133,13 +133,15 @@ Use this procedure to replace a member of a replica set when the host
 name has changed. This procedure preserves all existing configuration
 for a member, except its hostname/location.
 
-Replacing a member is useful if you have an existing configuration
-and only want to change the hostname of a member rather than completely
-remove all configurations related to the existing/previous set member.
+You may need to replace a replica set member if you want to replace an
+existing system and only need to change the hostname rather than
+completely replace all configured options related to the previous
+member.
 
 Use :method:`rs.reconfig()` to change the value of the
 :data:`members[n].host` field to reflect the new hostname or port
-number. :method:`rs.reconfig()` will not change the value of :data:`members[n]._id`. 
+number. :method:`rs.reconfig()` will not change the value of
+:data:`members[n]._id`.
 
 
 .. code-block:: javascript