doc: add STW metrics to release notes

For #63340.
For #61422.

Change-Id: Ib74bb54b0450e96b7f4b7eb7ba2ae7ac2d40171a
Reviewed-on: https://go-review.googlesource.com/c/go/+/547095
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>

doc/go1.22.html

@@ -638,16 +638,30 @@ defer func() {
 
 <dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics/">runtime/metrics</a></dt>
   <dd>
+    <p><!-- https://go.dev/issue/63340 -->
+      Four new histogram metrics
+      <code>/sched/pauses/stopping/gc:seconds</code>,
+      <code>/sched/pauses/stopping/other:seconds</code>,
+      <code>/sched/pauses/total/gc:seconds</code>, and
+      <code>/sched/pauses/total/other:seconds</code> provide additional details
+      about stop-the-world pauses.
+      The "stopping" metrics report the time taken from deciding to stop the
+      world until all goroutines are stopped.
+      The "total" metrics report the time taken from deciding to stop the world
+      until it is started again.
+    </p>
+
+    <p><!-- https://go.dev/issue/63340 -->
+      The <code>/gc/pauses:seconds</code> metric is deprecated, as it is
+      equivalent to the new <code>/sched/pauses/total/gc:seconds</code> metric.
+    </p>
+
     <p><!-- https://go.dev/issue/57071 -->
       <code>/sync/mutex/wait/total:seconds</code> now includes contention on
       runtime-internal locks in addition to
       <a href="/pkg/sync#Mutex"><code>sync.Mutex</code></a> and
       <a href="/pkg/sync#RWMutex"><code>sync.RWMutex</code></a>.
     </p>
-
-    <p><!-- https://go.dev/issue/63340 -->
-      TODO: <a href="https://go.dev/issue/63340">https://go.dev/issue/63340</a>: provide histogram of all STW events
-    </p>
   </dd>
 </dl><!-- runtime/metrics -->