runtime/trace: fix syntax errors in NewTask doc example

Fixes #27406

Change-Id: I9c6f5bac5b26558fa7628233c74a62faf676e811
GitHub-Last-Rev: 29d19f719316b486224a15a50556465811985edf
GitHub-Pull-Request: golang/go#27437
Reviewed-on: https://go-review.googlesource.com/132775Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/trace/annotation.go

@@ -24,13 +24,13 @@ type traceContextKey struct{}
 // If the end function is called multiple times, only the first
 // call is used in the latency measurement.
 //
-//   ctx, task := trace.NewTask(ctx, "awesome task")
-//   trace.WithRegion(ctx, prepWork)
+//   ctx, task := trace.NewTask(ctx, "awesomeTask")
+//   trace.WithRegion(ctx, "preparation", prepWork)
 //   // preparation of the task
 //   go func() {  // continue processing the task in a separate goroutine.
 //       defer task.End()
-//       trace.WithRegion(ctx, remainingWork)
-//   }
+//       trace.WithRegion(ctx, "remainingWork", remainingWork)
+//   }()
 func NewTask(pctx context.Context, taskType string) (ctx context.Context, task *Task) {
 	pid := fromContext(pctx).id
 	id := newID()