Followup to #4511: add link from decorator glossary entry to definition.
diff --git a/Doc/glossary.rst b/Doc/glossary.rst
index f3d86c3..2894f35 100644
--- a/Doc/glossary.rst
+++ b/Doc/glossary.rst
@@ -123,6 +123,9 @@
          def f(...):
              ...
 
+      See :ref:`the documentation for function definition <function>` for more
+      about decorators.
+
    descriptor
       Any *new-style* object which defines the methods :meth:`__get__`,
       :meth:`__set__`, or :meth:`__delete__`.  When a class attribute is a