add react hello world

src/Mine/SeekerBundle/Resources/views/Game/play.html.twig

@@ -0,0 +1,19 @@
+{% extends '::base.html.twig' %}
+
+{% block body %}
+    <div id="example"></div>
+    <script type="text/babel">
+        ReactDOM.render(
+                <h1>Hello, world!</h1>,
+                document.getElementById('example')
+        );
+    </script>
+{% endblock %}
+
+{% block javascripts %}
+    {{ parent() }}
+
+    <script src="{{ asset('bundles/mineseeker/js/src/build/react.js') }}"></script>
+    <script src="{{ asset('bundles/mineseeker/js/src/build/react-dom.js') }}"></script>
+    <script src="https://unpkg.com/babel-core@5.8.38/browser.min.js"></script>
+{% endblock %}