Provide instructional text in command line on completion of generation

[cmalven]

v1 of the generator outputs helpful text after a successful run to help the user understand what steps are expected next.

v2 does some of that, but it does a much more incomplete job because the combination of generators run will affect what the resulting text should be. For instance almost all projects currently supported by the generator will have a "next step" including the following:

cd project-name
yarn start

But that depends on having some kind of a build step, which may or may not be present. Still, I think we need to come up with some way of including this super helpful information.