cmd/go: if GOPATH and GOROOT are the same, refer to wiki page
This gives us a place to clarify what the problem is
and how people should fix it.
For #65656
Fixes #70093
Change-Id: I555399c52e9b72a7a66f0bd38df178c0efad6c27
Reviewed-on: https://go-review.googlesource.com/c/go/+/623815 Reviewed-by: Sam Thanawalla <samthanawalla@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>