Update README with branch-based instructions
Merge branch 'uses-build-script-two-working-externals-and-one-broken' of https://github.com/jfsiii/browserify-shim-nvd3 into uses-build-script-two-working-externals-and-one-broken

* 'uses-build-script-two-working-externals-and-one-broken' of https://github.com/jfsiii/browserify-shim-nvd3:
  Update README with branch-based instructions
  Move CLI-based browserify steps to build.js
  Show that jquery & d3 work as expected, but not nvd3