docs/references: Use the newer RFC for ChaCha20-Poly1305

Change-Id: Ie98e5c4ece7e3b8e180daed9ea5d1519221d1277
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/93149
Reviewed-by: Adam Langley <agl@google.com>
Presubmit-BoringSSL-Verified: boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>

docs/references.md

diff --git a/docs/references.md b/docs/references.md
index 3ad9830..c561975 100644
--- a/docs/references.md
+++ b/docs/references.md
@@ -8,7 +8,7 @@
 
 * [AES (FIPS 197)](https://csrc.nist.gov/pubs/fips/197/final)
 * [GCM (SP 800-38D)](https://csrc.nist.gov/pubs/sp/800/38/d/final)
-* [ChaCha20-Poly1305 (RFC 7539)](https://www.rfc-editor.org/rfc/rfc7539.html)
+* [ChaCha20-Poly1305 (RFC 8439)](https://www.rfc-editor.org/rfc/rfc8439.html)
 * [AES-GCM-SIV (RFC 8452)](https://www.rfc-editor.org/rfc/rfc8452.html)
 * [RSA (PKCS #1, RFC 8017)](https://www.rfc-editor.org/rfc/rfc8017.html)
 * [X25519 (RFC 7748)](https://www.rfc-editor.org/rfc/rfc7748.html)