Add version tags to sys.{get,set}switchinterval
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 5d1a7c0..44ac6ee 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -353,6 +353,8 @@
    Return the interpreter's "thread switch interval"; see
    :func:`setswitchinterval`.
 
+   .. versionadded:: 3.2
+
 
 .. function:: _getframe([depth])
 
@@ -713,6 +715,8 @@
    is the operating system's decision.  The interpreter doesn't have its
    own scheduler.
 
+   .. versionadded:: 3.2
+
 
 .. function:: settrace(tracefunc)