Fix typo in warning (#3738)

Author: lorand-horvath

src/create-route-map.js

@@ -129,7 +129,7 @@ function addRouteRecord (
           `Named Route '${route.name}' has a default child route. ` +
             `When navigating to this named route (:to="{name: '${
               route.name
-            }'"), ` +
+            }'}"), ` +
             `the default child route will not be rendered. Remove the name from ` +
             `this route and use the name of the default child route for named ` +
             `links instead.`