recommend requests library (closes #23989)

Patch by Van Lindberg.
diff --git a/Doc/library/urllib2.rst b/Doc/library/urllib2.rst
index f599894..3fe4f25 100644
--- a/Doc/library/urllib2.rst
+++ b/Doc/library/urllib2.rst
@@ -18,6 +18,11 @@
 URLs (mostly HTTP) in a complex world --- basic and digest authentication,
 redirections, cookies and more.
 
+.. seealso::
+
+    The `Requests package <http://requests.readthedocs.org/>`_
+    is recommended for a higher-level http client interface.
+
 
 The :mod:`urllib2` module defines the following functions: