docs: remove references to vgo (google/go-cloud#206)
docs: remove references to vgo (google/go-cloud#206)

We should be instructing users to run stable things, and more
adventurous folks can adapt to use Go modules. I just ran the test suite
locally from a `go get` and it compiled and ran fine.

Updates google/go-cloud#78
Updates google/go-cloud#208

google/wire,google/wire