Fix typo (#48)

Author: martijndwars

nodejs/README.md

@@ -16,7 +16,7 @@ var parameters = {
 };
 var encrypted = ece.encrypt(data, parameters);
 
-var decrypted = ece.encrypt(encrypted, parameters);
+var decrypted = ece.decrypt(encrypted, parameters);
 
 require('assert').equal(decrypted.compare(data), 0);
 ```