doc: retro-actively document removal of tlkskyber GODEBUG flag

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

Change-Id: I7e6aeefc7dbf5819c441887dea304bb6716478ae
Reviewed-on: https://go-review.googlesource.com/c/website/+/820181
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Bypass: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>

_content/doc/go1.27.md

diff --git a/_content/doc/go1.27.md b/_content/doc/go1.27.md
index 2b9c213..4c64683 100644
--- a/_content/doc/go1.27.md
+++ b/_content/doc/go1.27.md
@@ -442,6 +442,13 @@
 and `x509keypairleaf` (added in [Go 1.23](/doc/godebug#go-123))
 `GODEBUG` settings have been removed permanently.
 
+<!-- go.dev/issue/72111 -->
+
+The `tlskyber` `GODEBUG` setting (added in [Go 1.23](/doc/godebug#go-123))
+was removed in [Go 1.24](/doc/godebug#go-124) but the removal was not
+documented in the [release notes for Go 1.24](/doc/go1.24.md) at that time;
+it is documented now.
+
 #### [`crypto/x509`](/pkg/crypto/x509/)
 
 <!-- 6-stdlib/99-minor/crypto/x509/75260.md -->