Fix link in usage.rst

docs/usage.rst

@@ -39,7 +39,7 @@ will do some final calculations in case the detector didn’t hit its
 minimum confidence threshold earlier. Then ``detector.result`` will be a
 dictionary containing the auto-detected character encoding and
 confidence level (the same as the ``chardet.detect`` function 
-`returns <usage.html#example.basic.detect>`__).
+`returns <usage.html#example-using-the-detect-function>`__).
 
 
 Example: Detecting encoding incrementally