ui: add link to www.proxmox.com for subscription plans

www/Dashboard.js

@@ -394,7 +394,7 @@ Ext.define('PBS.dashboard.SubscriptionInfo', {
 		break;
 	    case 0:
 		icon = 'times-circle critical';
-		message = gettext('This node does not have a subscription.');
+		message = gettext('<h1>No valid subscription</h1>' + PBS.Utils.noSubKeyHtml);
 		break;
 	    default:
 		throw 'invalid subscription status';

www/Utils.js

@@ -50,6 +50,8 @@ Ext.define('PBS.Utils', {
 	}
     },
 
+    noSubKeyHtml: 'You do not have a valid subscription for this server. Please visit <a target="_blank" href="https://www.proxmox.com/proxmox-backup-server/pricing">www.proxmox.com</a> to get a list of available options.',
+
     getDataStoreFromPath: function(path) {
 	return path.slice(PBS.Utils.dataStorePrefix.length);
     },