Add version{added,changed} for lock timeout support.
diff --git a/Doc/library/_thread.rst b/Doc/library/_thread.rst
index d4ff6de..80fad68 100644
--- a/Doc/library/_thread.rst
+++ b/Doc/library/_thread.rst
@@ -109,6 +109,8 @@
    :meth:`Lock.acquire`. Specifiying a timeout greater than this value will
    raise an :exc:`OverflowError`.
 
+   .. versionadded:: 3.2
+
 
 Lock objects have the following methods:
 
@@ -132,6 +134,9 @@
    The return value is ``True`` if the lock is acquired successfully,
    ``False`` if not.
 
+   .. versionchanged:: 3.2
+      The *timeout* parameter is new.
+
 .. method:: lock.release()
 
    Releases the lock.  The lock must have been acquired earlier, but not