README should include documentation on use of babelrc: false option

[mattdsteele]

See babel/babel-loader#428 for a more detailed description of the issue.

The tl;dr is that if you're using babelOptions in awesomeTypescriptLoaderOptions, anything in .babelrc will take precedence. This breaks expected usage for scenarios where you need two sets of Babel configs (example: one for Webpack, one for your build tools).

This loader works fine so long as you set `"babelrc": false:

  "awesomeTypescriptLoaderOptions": {
    "useBabel": true,
    "babelOptions": {
      "babelrc": false, /* Important line */
      "presets": [
        ["env", { "targets": "last 2 versions, ie 11", "modules": false }]
      ]
    }
  }  

But this wasn't documented and I had to dig around to discover the option.