Improve dev vs production distinctions

react-ui/src/App.js

@@ -8,17 +8,34 @@ class App extends Component {
       <div className="App">
         <header className="App-header">
           <img src={logo} className="App-logo" alt="logo" />
-          <p>
-            Edit <code>src/App.js</code> and save to reload.
-          </p>
-          <a
-            className="App-link"
-            href="https://reactjs.org"
-            target="_blank"
-            rel="noopener noreferrer"
-          >
-            Learn React
-          </a>
+          { process.env.NODE_ENV === 'production' ?
+
+              <p>
+                This is a production build from create-react-app
+                <br/>
+                <br/>
+                <a
+                  className="App-link"
+                  href="https://github.com/mars/heroku-cra-node"
+                >
+                  React + Node deployment on Heroku
+                </a>
+              </p>
+
+            : <p>
+                Edit <code>src/App.js</code> and save to reload.
+                <br/>
+                <br/>
+                <a
+                  className="App-link"
+                  href="https://reactjs.org"
+                  target="_blank"
+                  rel="noopener noreferrer"
+                >
+                  Learn React
+                </a>
+              </p>
+          }
         </header>
       </div>
     );