note abcs of int and float (closes #11977)

Doc/library/stdtypes.rst

@@ -460,6 +460,9 @@ Notes:
 Additional Methods on Integer Types
 -----------------------------------
 
+The int type implements the :class:`numbers.Integral` :term:`abstact base
+class`. In addition, it provides one more method
+
 .. method:: int.bit_length()
 .. method:: long.bit_length()
 
@@ -491,7 +494,8 @@ Additional Methods on Integer Types
 Additional Methods on Float
 ---------------------------
 
-The float type has some additional methods.
+The float type implements the :class:`numbers.Real` :term:`abstract base
+class`. float also has the following additional methods.
 
 .. method:: float.as_integer_ratio()