bpo-33726, doc: Add short descriptions to PEP references in seealso (GH-7294)

diff --git a/Doc/reference/simple_stmts.rst b/Doc/reference/simple_stmts.rst
index bb1eea6..f98721c 100644
--- a/Doc/reference/simple_stmts.rst
+++ b/Doc/reference/simple_stmts.rst
@@ -353,8 +353,15 @@
 
 .. seealso::
 
-   :pep:`526` - Variable and attribute annotation syntax
+   :pep:`526` - Syntax for Variable Annotations
+      The proposal that added syntax for annotating the types of variables
+      (including class variables and instance variables), instead of expressing
+      them through comments.
+
    :pep:`484` - Type hints
+      The proposal that added the :mod:`typing` module to provide a standard
+      syntax for type annotations that can be used in static analysis tools and
+      IDEs.
 
 
 .. _assert: