don't remove self from example code in the HTML output (closes #13223)

Patch by Víctor Terrón.

Lib/test/pydoc_mod.py

@@ -15,6 +15,16 @@ class B(object):
     NO_MEANING = "eggs"
     pass
 
+class C(object):
+    def say_no(self):
+        return "no"
+    def get_answer(self):
+        """ Return say_no() """
+        return self.say_no()
+    def is_it_true(self):
+        """ Return self.get_answer() """
+        return self.get_answer()
+
 def doc_func():
     """
     This function solves all of the world's problems: