Fix README for base64 uploads

Author: mynetx

README.md

@@ -325,7 +325,7 @@ base64-encoded. **First** you send each image to Twitter, like this:
 
 ```javascript
 var params = {
-    "media": "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"
+    "media_data": "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"
 );
 cb.__call(
     "media_upload",