doc: retro-actively document removal of tlkskyber GODEBUG flag

Per comment in CL 784221.
For golang/go#72111.
For golang/go#81038.

Change-Id: Ie2654e20f85964fef921f1101fc92c88e5bbc56a
Reviewed-on: https://go-review.googlesource.com/c/website/+/820560
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Bypass: Robert Griesemer <gri@google.com>

_content/doc/go1.24.md

diff --git a/_content/doc/go1.24.md b/_content/doc/go1.24.md
index 9499749..5d09ff6 100644
--- a/_content/doc/go1.24.md
+++ b/_content/doc/go1.24.md
@@ -497,6 +497,11 @@
 field lists the IDs of the extensions received in the Client Hello message.
 This can be useful for fingerprinting TLS clients.
 
+<!-- go.dev/issue/72111, documented retro-actively after Go 1.27 release -->
+
+The `tlskyber` `GODEBUG` setting (added in [Go 1.23](/doc/godebug#go-123))
+has been removed.
+
 #### [`crypto/x509`](/pkg/crypto/x509/)
 
 <!-- go.dev/issue/41682 -->