website: workspaces tutorial is broken

[hyangah]

https://go.dev/doc/tutorial/workspaces

Following the section "Create a module for your code"
users face errors

hello$ go run example.com/hello
hello.go:6:2: no required module provides package golang.org/x/example/stringutil; to add it:
	go get golang.org/x/example/stringutil
hello$ 

This is due to the recent changes in the golang.org/x/example repo - stringutil package is no longer there.

[gopherbot]

Change https://go.dev/cl/515238 mentions this issue: _content: update for golang.org/x/example changes