_content/doc: add CL 514997 to list in QUIC comment for go1.21.html

Change-Id: I9649bd9b02cb36b843acbe30b467de1ebfa52c38
Reviewed-on: https://go-review.googlesource.com/c/website/+/516135
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Damien Neil <dneil@google.com>

_content/doc/go1.21.html

@@ -606,7 +606,7 @@ Do not send CLs removing the interior tags from such phrases.
       has been reverted, and is now set for resumed connections that support Extended Master Secret.
     </p>
 
-    <p><!-- https://go.dev/issue/44886, https://go.dev/issue/60107, CL 493655, CL 496995 -->
+    <p><!-- https://go.dev/issue/44886, https://go.dev/issue/60107, CL 493655, CL 496995, CL 514997 -->
       The new <a href="/pkg/crypto/tls/#QUICConn"><code>QUICConn</code></a> type
       provides support for QUIC implementations, including 0-RTT support. Note
       that this is not itself a QUIC implementation, and 0-RTT is still not