Add missing quote.

Without this quote Angular CLI is not able to execute any of  the
schematics.

Author: piotrtomiak

src/lib/schematics/collection.json

@@ -28,7 +28,7 @@
       "description": "Create a component with a responsive sidenav for navigation",
       "factory": "./nav/index",
       "schema": "./nav/schema.json",
-      "aliases": [ "material-nav", "materialNav ]
+      "aliases": [ "material-nav", "materialNav" ]
     },
     // Creates a address form component
     "addressForm": {