title: What is the purpose of a manifest.json file in an Angular project
body: <p>First of all I didn't know anything about the potential existence of such file in the context of an Angular 5+ Project. I have a running Angular 5 project which doesn't have this manifest.json file in it. I decided to add <a href="https://angular.io/guide/service-worker-intro" rel="noreferrer">service worker</a> facility to improve the performance of the application. The service worker didn't get activated and I did a little research on the problem and came across the following <a href="https://github.com/angular/angular-cli/issues/8779" rel="noreferrer">open github issue</a> in which some people mentioned they fixed the issue using a manifest.json. What is this file? Why couldn't it be part of the Angular CLI config? On what condition would you require one? Where is the potential documentation?</p>