Added note on assigning correct file permissions

Gives an example for the _www Apache user.
(cherry picked from commit 113aa5a)

Author: mikeedwards

README.md

@@ -60,6 +60,12 @@ You do not need to configure your `/etc/hosts` file for `local.*` because `jquer
 
     RewriteRule . index.php [L]
     ```
+1. Make sure that you have assigned your WordPress files and directories the correct permissions.  
+For example, if your WordPress files are in the directory ```wordpress```, and you are running Apache under Mac OS X with the ```_www``` user:
+    ```
+    sudo chown -R _www wordpress
+    sudo chmod -R g+w wordpress
+    ```
 
 1. Go to `http://local.jquery.com` and walk through the standard WordPress installation. `web-base-template` includes a special install script that will initialize the entire network.