design/draft-workspace.md: address more comments made on mailing list
design/draft-workspace.md: address more comments made on mailing list

Change-Id: I3c5de0e829e5dbbf2283bd881757ee3b0426c807
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/311509
Trust: Michael Matloob <4562438b12c14e81a47550acde616ff328a909f8@golang.org>
Run-TryBot: Michael Matloob <4562438b12c14e81a47550acde616ff328a909f8@golang.org>
Reviewed-by: Michael Matloob <4562438b12c14e81a47550acde616ff328a909f8@golang.org>

golang/proposal,golang/proposal