add SEED CBC vectors from rfc 4196
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index b580855..d2e9548 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -78,6 +78,7 @@
 * IDEA (CBC, CFB, OFB) generated by this project.
   See: :doc:`/development/custom-vectors/idea`
 * SEED (ECB) from :rfc:`4269`.
+* SEED (CBC) from :rfc:`4196`.
 
 Two factor authentication
 ~~~~~~~~~~~~~~~~~~~~~~~~~