Make the route name error more helpful

As a developer I have no clue what "Invalid route name" means. If the
exception gives me a hint I might find it easier to figure out why my
route triggers this error.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

lib/private/AppFramework/Routing/RouteConfig.php

@@ -130,7 +130,7 @@ protected function processRoute(array $route, string $routeNamePrefix = ''): voi
 
 		$split = explode('#', $name, 2);
 		if (count($split) !== 2) {
-			throw new \UnexpectedValueException('Invalid route name');
+			throw new \UnexpectedValueException('Invalid route name: use the format foo#bar to reference FooController::bar');
 		}
 		[$controller, $action] = $split;
 

lib/private/AppFramework/Routing/RouteParser.php

@@ -93,7 +93,7 @@ private function processRoute(array $route, string $appName, string $routeNamePr
 
 		$split = explode('#', $name, 2);
 		if (count($split) !== 2) {
-			throw new \UnexpectedValueException('Invalid route name');
+			throw new \UnexpectedValueException('Invalid route name: use the format foo#bar to reference FooController::bar');
 		}
 		[$controller, $action] = $split;