angular-cli no longer supports the --mobile flag

You probably want to update the guides, specifically this page:
mobile-toolkit/guides/cli-setup.md

You make reference to the --mobile flag. This was removed from angular-cli some time ago. You now must create the manifest file on your own manually. And I could be wrong but I think the way ng serve works requires that the manifest gets placed in the assets directory or else it just 404's.