Added some more documentation to install the babel-preset-react-app making it more clear on how to get started with this preset outside of create-react-app.
* Add note for using CHOKIDAR_USEPOLLING in virtual machines to enable HMR
* Use br in react-scripts template README md
* Use br in md for new line breaks
* Update troubleshooting HMR to allow for VMs running Windows
* Fix up the instructions