Update README.md

Amine Mouafik · Amine Mouafik · commit a83ff49c329e · 2014-12-13T00:02:24.000+07:00
diff --git a/README.md b/README.md
@@ -5,3 +5,8 @@
 ## Installation
 
 `npm install node-authorize-net`
+
+## Usage
+
+This SDK is natively compatible with [42-cent](https://github.com/continuous-software/42-cent).  
+It implements the [BaseGateway](https://github.com/continuous-software/42-cent-base) API.
