Clarify docs for --config flag

Fixes postcss#233

Author: RyanZim

README.md

@@ -51,7 +51,7 @@ Advanced options:
             directory, for use with --dir                               [string]
   --poll    Use polling for file watching. Can optionally pass polling interval;
             default 100 ms
-  --config  Set a custom path to look for a config file                 [string]
+  --config  Set a custom directory to look for a config file            [string]
 
 Options:
   --version  Show version number                                       [boolean]

lib/args.js

@@ -118,7 +118,7 @@ Usage:
     implies: 'watch'
   })
   .option('config', {
-    desc: 'Set a custom path to look for a config file',
+    desc: 'Set a custom directory to look for a config file',
     type: 'string'
   })
   .version(version)