cmd/go: add space after comma in 'go help test'
This PR fixes a simple typo. It adds a space after a comma. Noticed while looking at `go help test` output.
Change-Id: I5b54f4da0d08a056bffc04899983d858dfa91043
GitHub-Last-Rev:
da9cab5eb946523b8783aafe4f05f516e4a77437
GitHub-Pull-Request: golang/go#53931
Reviewed-on: https://go-review.googlesource.com/c/go/+/418034
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>