_content/doc: fix go mod edit for PowerShell
_content/doc: fix go mod edit for PowerShell

"-replace=foo.com=bar.com" triggers this bug in PowerShell:
https://github.com/PowerShell/PowerShell/issues/6291
The go command accepts "-replace foo.com=bar.com" just fine. Use that
instead.

Fixes #44924.

Change-Id: I854ea86282db425a2707c641b0500208b4869870
Reviewed-on: https://go-review.googlesource.com/c/website/+/330229
Trust: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
Run-TryBot: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Steve Traut <af4cad49c6f706d4616eefecc2c596e86c262fed@google.com>

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website