Hot Reloading Bootstrap 4 Example HTML with React via nwb v0.19

Part of "Using Bootstrap 4 from source with React and nwb" - / using-bootstrap-4-from...
Example of copying and pasting Bootstrap 4 example HTML into a React component and using webpack-dev-server's syntax error overlays to correct problems.
All changes are hot-reloaded using the app development setup nwb [1] provides, with Sass loading enabled by installing the nwb-sass [2] plugin.
Sass variables are then edited to show that they're also hot-reloaded.
[1] github.com/ins...
[2] github.com/ins...