fix --device info casing

Author: montmanu

lib/mapping.js

@@ -166,7 +166,7 @@ var options = {
       name: 'device',
       api: 'mobileDevice',
       param: 'string',
-      info: 'Device name from mobile_devices.ini to use for mobile emulation (only when mobile=1 is specified to enable emulation and only for Chrome)'
+      info: 'device name from mobile_devices.ini to use for mobile emulation (only when mobile=1 is specified to enable emulation and only for Chrome)'
     },
     'timeline': {
       name: 'timeline',