Issue #15582: Add a whatsnew entry for inspect.getdoc() changes in 3.5.

Patch by Martin Panter.

Doc/library/inspect.rst

@@ -423,6 +423,9 @@ Retrieving source code
    a class, a method, a property or a descriptor, retrieve the documentation
    string from the inheritance hierarchy.
 
+   .. versionchanged:: 3.5
+      Documentation strings are now inherited if not overridden.
+
 
 .. function:: getcomments(object)
 

Doc/whatsnew/3.5.rst

@@ -1139,6 +1139,13 @@ Changes in the Python API
   ``True`` when finding the empty string and the indexes are completely out of
   range.  See :issue:`24284`.
 
+* The :func:`inspect.getdoc` function now returns documentation strings
+  inherited from base classes.  Documentation strings no longer need to be
+  duplicated if the inherited documentation is appropriate.  To suppress an
+  inherited string, an empty string must be specified (or the documentation
+  may be filled in).  This change affects the output of the :mod:`pydoc`
+  module and the :func:`help` function.  See :issue:`15582`.
+
 Changes in the C API
 --------------------