Repo retirement notice for 4.22

[andygup]

At 4.22 (late Q4 2021) this repo will no longer be supported. This issue supersedes and closes #90.

We recommend migrating from AMD modules to using @arcgis/core ES modules with the latest Angular as demonstrated in this sample: https://github.com/Esri/jsapi-resources/tree/master/esm-samples/jsapi-angular-cli. The Angular team officially recognize ES modules as a best practice for creating applications with their framework: https://angular.io/guide/ngmodule-vs-jsmodule#javascript-modules-files-containing-code.

For more information on migrating from AMD to ES modules see the Introduction to tooling Guide topic in the SDK.

And last but not least, thank you to everyone that used this repo, it's been part of a continuous family of repos dating back over 9 years. Starting with AngularJS (v1.x) all the way up to Angular 13, which was just released in November 2021, we have continuously offered samples, such as this one, that demonstrate patterns for integrating with the ArcGIS JS API, and that have been used in numerous applications worldwide.

[andygup]

Closing.