📚 revise build docs for heroku-postbuild

README.md

@@ -11,8 +11,8 @@ To deploy a frontend-only React app, use the static-site optimized
 A combo of two npm projects, the backend and the frontend. So there are two `package.json` configs.
 
   1. [`package.json`](package.json) for [Node server](server/) & [Heroku deploy](https://devcenter.heroku.com/categories/deployment)
-      * `postinstall` script builds the React UI webpack bundle
-      * `cacheDirectories` includes `react-ui/node_modules/` to optimize deploy to Heroku
+      * `heroku-postbuild` script compiles the webpack bundle during deploy
+      * `cacheDirectories` includes `react-ui/node_modules/` to optimize build time
   2. [`react-ui/package.json`](react-ui/package.json) for [React web UI](react-ui/)
       * generated by [create-react-app](https://github.com/facebookincubator/create-react-app)
 
@@ -38,7 +38,7 @@ This deployment will automatically:
   * detect [Node buildpack](https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-nodejs)
   * build the app with
     * `npm install` for the Node server
-    * `postinstall` to build the webpack bundle from create-react-app
+    * `heroku-postbuild` for create-react-app
   * launch the web process with `npm start`
     * serves `../react-ui/build/` as static files
     * customize by adding API, proxy, or route handlers/redirectors