Add a few missing source links from 2.7 and harmonize lib docs headers
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst
index e5d13f3..2359dd1 100644
--- a/Doc/library/concurrent.futures.rst
+++ b/Doc/library/concurrent.futures.rst
@@ -4,11 +4,11 @@
.. module:: concurrent.futures
:synopsis: Execute computations concurrently using threads or processes.
+.. versionadded:: 3.2
+
**Source code:** :source:`Lib/concurrent/futures/thread.py`
and :source:`Lib/concurrent/futures/process.py`
-.. versionadded:: 3.2
-
--------------
The :mod:`concurrent.futures` module provides a high-level interface for