Reformat AES CTR vectors to use NIST loader & document their source properly
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 3b8632e..97b5c34 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -47,7 +47,8 @@
Symmetric Ciphers
~~~~~~~~~~~~~~~~~
-* AES (CBC, CFB, CTR, ECB, GCM, OFB) from `NIST CAVP`_.
+* AES (CBC, CFB, ECB, GCM, OFB) from `NIST CAVP`_.
+* AES CTR from :rfc:`3686`.
* 3DES (CBC, CFB, ECB, OFB) from `NIST CAVP`_.
* ARC4 from :rfc:`6229`.
* Blowfish (CBC, CFB, ECB, OFB) from `Bruce Schneier's vectors`_.