Add basic SEO details

Author: Mykolas

services/app/src/index.html

@@ -6,6 +6,10 @@
       name="viewport"
       content="width=device-width, initial-scale=1.0, maximum-scale=1.0,user-scalable=0"
     />
+    <meta name="description" content="The consensus-based chess inspired task estimation game." />
+    <meta name="keywords" content="planning-poker, estimation, chess, game" />
+    <meta name="author" content="Zenitech" />
+    <meta name="robots" content="index, follow"/>
     <title>Planning Chess</title>
     <link href="static/favicon.ico" rel="shortcut icon" />
   </head>