doc(jest-angular): update README.md

Author: chihab

examples/apps/ng-app-cli/setup-jest.ts

@@ -1,6 +1,6 @@
+import 'jest-preset-angular/setup-jest.mjs';
 import { env } from '@dotenv-run/core';
 env({ root: '../../..', files: ['.env', '.env.app'] });
-import 'jest-preset-angular/setup-jest.mjs';
 
 import '@angular/localize/init';
 import { TextEncoder } from 'util';

packages/jest-angular/README.md

@@ -1,24 +1,30 @@
 ## Install
 
+The package requires `jest-preset-angular@14` to be installed as a peer dependency.
+
 ```sh
 npm install --save-dev @dotenv-run/jest-angular
 ```
 
 ## Usage
 
-Add the following to your `jest.config.js`:
+Add the following to your `jest.config.js`, more information can be found in the [jest-preset-angular](https://thymikee.github.io/jest-preset-angular/docs/guides/esm-support/).
+
+ESM support is required for Jest to understand `import.meta.env` notation.
 
 ```js
 const jestConfig = {
+  // Required for ESM support
   preset: "jest-preset-angular/presets/defaults-esm",
   setupFilesAfterEnv: ["<rootDir>/setup-jest.ts"],
   testMatch: ["<rootDir>/src/app/**/*.(spec|jest).ts"],
-  cache: false,
   moduleNameMapper: {
     "^rxjs(/operators$)?$":
       "<rootDir>/node_modules/rxjs/dist/bundles/rxjs.umd.js",
     tslib: "<rootDir>/node_modules/tslib/tslib.es6.mjs",
   },
+
+  // @dotenv-run/jest-angular transformer
   transform: {
     "^.+\\.(ts)$": [
       "@dotenv-run/jest-angular",
@@ -32,15 +38,18 @@ const jestConfig = {
 export default jestConfig;
 ```
 
-Create a `setup-jest.ts` file in your project root:
+Add the following to your `setup-jest.ts` file.
 
 ```ts
+// Required for ESM support
+import "jest-preset-angular/setup-jest.mjs";
+
+// Load environment variables for Jest
 import { env } from "@dotenv-run/core";
 env({ root: "../../..", files: [".env", ".env.app"] });
-import "jest-preset-angular/setup-jest.mjs";
 ```
 
-Run your tests with `jest`.
+Run your tests with `jest`. More information can be found in the [Jest documentation](https://jestjs.io/docs/ecmascript-modules).
 
 ```sh
 NODE_OPTIONS=--experimental-vm-modules npx jest