Add banner to describe state of application

Author: Panda4817

src/App.js

@@ -11,6 +11,13 @@ import ScrollToTop from './components/ScrollToTop/ScrollToTop'
 const App = () => (
     <Router>
         <ScrollToTop />
+        <div class="alert alert-info text-center" role="alert">
+            <h1 class="alert-heading">Update</h1>
+            <p class="lead">Unfortunately, due to server hosting costs, Picto backend server has been shutdown.</p>
+            <p class="lead">Until a cheaper option is found, without the backend server running, Picto is not playable.</p>
+            <p class="lead">Source code is available on <a href="https://github.com/Panda4817/Multiplayer-Pictionary-Frontend" class="alert-link">GitHub</a> if you wish to run it yourself.</p>
+            <p class="lead">Sorry for the inconvenience.</p>
+        </div>
         <Route path="/" exact component={Join} />
         <Route path="/join" component={Join} />
         <Route path="/game" component={Game} />