runtime/trace: comment newlines to restore correct doc summary

Fixes #26309

Change-Id: I0e0b61b885817e514aa46e299b00833f16e98b2a
Reviewed-on: https://go-review.googlesource.com/122898
Reviewed-by: Айнар Гарипов <gugl.zadolbal@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/trace/trace.go

@@ -82,10 +82,10 @@
 //
 //      ctx, task := trace.NewTask(ctx, "makeCappuccino")
 //      trace.Log(ctx, "orderID", orderID)
-
+//
 //      milk := make(chan bool)
 //      espresso := make(chan bool)
-
+//
 //      go func() {
 //              trace.WithRegion(ctx, "steamMilk", steamMilk)
 //              milk <- true