all: fix some comments

Change-Id: I021c01f6be65f1581c3e272004c366d4457404b0
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/713081
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>