Fix markup errors and update pydoc topics.
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index a64424d..17f8fde 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -1135,7 +1135,7 @@
 --
 
 It is now possible to register callbacks invoked by the garbage collector
-before and after collection using the new :`data:`~gc.callbacks` list.
+before and after collection using the new :data:`~gc.callbacks` list.
 
 
 hmac