fix for flow error on html loading by adding mimic typing of expected output of raw-loader

.flowconfig

// place this one in the [options] section in your flowconfig

module.name_mapper='^raw-loader!\(.*\.html?\)' -> '<PROJECT_ROOT>/flow-typed/raw-loader.js'

raw-loader.js

// I have placed this in flow-typed directory under root directory of my project
// but this solution does not work

// @flow
const s: string = "";
export default s;