Doc: Typescript support

[lifeart]

Writing this issue to show how we could have typescript compilation support using babel.

function es6() {
  return browserify({
    entries: './src/js/main.js',
    extensions: ['.js', '.ts'],
  })
    .transform(
      babelify.configure({
        "presets": [
          "@babel/preset-env", 
          "module:@babel/preset-typescript"
        ],
        "plugins": ["@babel/proposal-class-properties"]
      }),
      { extensions: ['.js', '.ts'] },
    )
    .bundle()
    .pipe(source('main.js'))
}

In short, we have to add .ts extension to browserify config, and specify proper babel plugins (@babel/preset-typescript)