Minor typo

Author: puentesarrin

source/administration/configuration.txt

@@ -64,7 +64,7 @@ following explanation:
   server to only listen for requests on the localhost IP. Only bind to
   secure interfaces that the application-level systems can access with
   access control provided by system network filtering
-  (i.e. ":term:`firewall`) systems.
+  (i.e. ":term:`firewall`").
 
 - :setting:`port` is ``27017``, which is the default
   MongoDB port for database instances. MongoDB can bind to any