design/draft-workspace.md: make some more clarifications
design/draft-workspace.md: make some more clarifications

Change-Id: I3173d99e13dcb841ee6ef44a2a00f0863b11cd85
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/312609
Trust: Michael Matloob <4562438b12c14e81a47550acde616ff328a909f8@golang.org>
Run-TryBot: Michael Matloob <4562438b12c14e81a47550acde616ff328a909f8@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <d7e82c3c07f92613bcbf9a1e88f6b96c13caa3b0@gmail.com>

golang/proposal,golang/proposal