Add a DATETIME example to fluent-react's hello-world

Author: stasm

fluent-react/examples/hello-world/src/App.js

@@ -7,6 +7,11 @@ export default function App() {
       <Localized id="title">
         <h1>Hello, world!</h1>
       </Localized>
+      <Localized id='today-is' $date={new Date()}>
+        <p>
+          {'Today is { DATETIME($date, month: "long", day: "numeric") }.'}
+        </p>
+      </Localized>
     </div>
   );
 }

fluent-react/examples/hello-world/src/l10n.js

@@ -5,9 +5,11 @@ import { negotiateLanguages } from 'fluent-langneg';
 const MESSAGES_ALL = {
   'pl': `
 title = Witaj świecie!
+today-is = Dziś jest { DATETIME($date, month: "long", day: "numeric") }.
   `,
   'en-US': `
 title = Hello, world!
+today-is = Today is { DATETIME($date, month: "long", day: "numeric") }.
   `,
 };