doc/articles/race_detector.html: add darwin/arm64

Updates #38485.

Change-Id: I46f515973c0a31d7c3e0e05ce006121c60c4041e
Reviewed-on: https://go-review.googlesource.com/c/go/+/268497


Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>