Add ARC note to readme

Author: soffes

Readme.markdown

@@ -8,12 +8,15 @@ SSZipArchive is a simple utility class for zipping and unzipping files. Features
 * Appending to zip files
 * Zipping files
 * Zipping NSData with a filename
+* Works in ARC and non-ARC projects
 
 ## Adding to your project
 
 1. Add `SSZipArchive.h`, `SSZipArchive.m`, and `minizip` to your project.
 2. Add the `libz` library to your target
 
+You don't need to do anything regarding ARC. SSZipArchive will detect if you're not using ARC and add the required memory management code.
+
 ## Usage
 
 ``` objective-c