Minor markup fixes

Author: Ed Costello

source/reference/mongos.txt

@@ -34,6 +34,8 @@ instance.
 Options
 -------
 
+.. binary:: mongos
+
 .. program:: mongos
 
 .. option:: --help, -h
@@ -247,8 +249,8 @@ Options
 
    .. versionadded:: 2.2
 
-   :option:`--localThreshold` affects the logic that binary:`mongos`
-   uses when selecting :term:`replica set` members to pass reads
+   :option:`--localThreshold` affects the logic that :program:`mongos`
+   uses when selecting :term:`replica set` members to pass read
    operations to from clients. Specify a value to
    :option:`--localThreshold` in milliseconds. The default value is
    ``15``, which corresponds to the default value in all of the client