Add instructions for using php 5.5 to README.md

README.md

@@ -277,6 +277,18 @@ magic_quotes_runtime = Off
 magic_quotes_sybase = Off
 ```
 
+CONFIGURING DRUSH FOR PHP 5.5
+-----------------------------
+
+Find your php-cli php.ini file using `drush status`, as described above.  
+Then, comment out the disable_functions line.
+
+In addition, if you are running on Linux, you may find that you need
+the php5-json package.  On Ubuntu, you can install it via:
+
+```apt-get install php5-json
+```
+
 INSTALLING DRUSH ON WINDOWS:
 ----------------------------