Go123Timer: fix title

Change-Id: I6ee403921b0e39d5f75fb68e228adc4a5d1db693
Reviewed-on: https://go-review.googlesource.com/c/wiki/+/582215
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/Go123Timer.md b/Go123Timer.md
index 10a4f7c..f1c92d7 100644
--- a/Go123Timer.md
+++ b/Go123Timer.md
@@ -1,4 +1,6 @@
-# Go 1.23 Timer Channel Changes
+---
+title: Go 1.23 Timer Channel Changes
+---
 
 Go 1.23 includes a new implementation of the channel-based timers
 created by [time.NewTimer](/pkg/time/#NewTimer), [time.After](/pkg/time/#After),