Add example of external dependencies

[kcrwfrd]

Figuring out how to include Lodash as a dependency in my library tripped me up quite a bit. I finally found guidance from http://survivejs.com/webpack_react/authoring_libraries/:

{
  devtool: 'source-map',
  output: {
    path: config.paths.dist,
    libraryTarget: 'umd',
    library: config.library
  },
  entry: config.paths.src,
  externals: {
    react: 'react'
    // Use more complicated mapping for lodash.
    // We need to access it differently depending
    // on the environment.
    lodash: {
      commonjs: 'lodash',
      commonjs2: 'lodash',
      amd: '_',
      root: '_'
    }
  },}
}

[krasimir]

Interesting. I didn't know that we may pass an object as a value in the externals. I updated the README so it contains such example. Thanks.

[kcrwfrd]

👍