fix packages path reference

@daydev first off great sample! Would you mind restructuring your example folder and pubspec so its easier to deal with? Having `pubspec.yaml` files within folders that pub will symlink `packages` is not always easy to deal with. If you do go that route I would suggest moving `example` folder to `app` folder. `app` folder will not get packages symlinked from the library in the parent directory. Another option is to move the example out into its own repo or move the entire thing into `web`. Thanks for the angular component :+1: