Added meta description

Author: Felix Hennig

template/layout.html

@@ -10,6 +10,8 @@
     <meta content="width=device-width, initial-scale=1.0" name="viewport" />
     <meta name="viewport" content="width=device-width, initial-scale=1">
 
+    <meta name="description" content="Detailed CustomResourceDefinitions (CRDs) reference documentation for the Stackable Data Platform." />
+
     <link rel="stylesheet" href="/static/css/root.css">
 </head>