Update tutorial.html: `javassist.util.HotSwapper`

The code path is fixed.

tutorial/tutorial.html

@@ -1092,7 +1092,7 @@ They have the same set of methods and fields.
 
 <p>Javassist provides a convenient class for reloading a class at runtime.
 For more information, see the API documentation of
-<code>javassist.tools.HotSwapper</code>.
+<code>javassist.util.HotSwapper</code>.
 
 <p><br>