Make generated doc in simple.rst more reliable

Sometimes `test_funcfast` would show up in the `setup` step in
the slowest test durations summary.

doc/en/example/simple.rst

@@ -363,14 +363,14 @@ out which tests are the slowest. Let's make an artificial test suite:
     import time
 
     def test_funcfast():
-        pass
-
-    def test_funcslow1():
         time.sleep(0.1)
 
-    def test_funcslow2():
+    def test_funcslow1():
         time.sleep(0.2)
 
+    def test_funcslow2():
+        time.sleep(0.3)
+
 Now we can profile which test functions execute the slowest::
 
     $ pytest --durations=3