Reference arc4.rst from the test-vectors.rst page
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 0b249cc..98e8d51 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -346,7 +346,9 @@
* 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`.
+* ARC4 (KEY-LENGTH: 40, 56, 64, 80, 128, 192, 256) from :rfc:`6229`.
+* ARC4 (KEY-LENGTH: 160) generated by this project.
+ See: :doc:`/development/custom-vectors/arc4`
* Blowfish (CBC, CFB, ECB, OFB) from `Bruce Schneier's vectors`_.
* Camellia (ECB) from NTT's `Camellia page`_ as linked by `CRYPTREC`_.
* Camellia (CBC, CFB, OFB) from `OpenSSL's test vectors`_.