doc/go1.16: tidy darwin/arm64 port section
doc/go1.16: tidy darwin/arm64 port section

For #40700.

Change-Id: I4f5d93e4ed13864f8b7dcc772d7ae074772b5a3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/275175
Trust: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>

CAFxX/go,cloudflare/go,cloudflare/go,nawawi/go,CAFxX/go,golang/go,golang/go,CAFxX/go,nawawi/go,golang/go,nawawi/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,cloudflare/go,golang/go,nawawi/go,cloudflare/go,cloudflare/go,golang/go,golang/go,nawawi/go,CAFxX/go,cloudflare/go,nawawi/go,cloudflare/go,golang/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go