Set-up instructions need info to get submodules

[alaframboise]

If you follow the steps as is the examples won't run. Need submodules via npm.

[kellyhutchins]

@alaframboise I ran through the steps here and the sample apps worked for me. The npm install step installs the dependencies including application-base-js

https://github.com/Esri/configurable-app-examples-4x-js#getting-started