Mark deprecated modules as such.
diff --git a/Doc/library/stringprep.rst b/Doc/library/stringprep.rst
index b0944e4..d2f269c 100644
--- a/Doc/library/stringprep.rst
+++ b/Doc/library/stringprep.rst
@@ -4,6 +4,7 @@
 
 .. module:: stringprep
    :synopsis: String preparation, as per RFC 3453
+   :deprecated:
 .. moduleauthor:: Martin v. Löwis <martin@v.loewis.de>
 .. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>