Update readme

Author: oohlaf

README.md

@@ -1,14 +1,28 @@
-# python-whirlpool
+python-whirlpool
+================
 
 This is just a wrapper to the Whirlpool C reference implementation. 
 The Whirlpool reference implementations are public domain, as is this code.
 
 Wrapper written by James Cleveland with help from #python on irc.freenode.net.
 
-USAGE:
+Wrapper modified by Olaf Conradi to use the hashlib interface.
+
+Usage
+-----
 
     import whirlpool
 
-    hashed_string = whirlpool.hash("Mystring")
+    wp = whirlpool.new("My String")
+    hashed_string = wp.hexdigest()
+
+    wp.update("My Salt")
+    hashed_string = wp.hexdigest()
+
+Deprecated usage
+----------------
+
+    import whirlpool
 
+    hashed_string = whirlpool.hash("My String")