docs: add storybookjs/testing-angular (#1355)

Author: jdegand

README.md

@@ -1070,6 +1070,7 @@ become an Angular expert.
 * [stryker-js](https://github.com/stryker-mutator/stryker-js) - Mutation testing for JavaScript and friends.
 * [msw](https://github.com/mswjs/msw) - Seamless REST/GraphQL API mocking library for browser and Node.js.
 * [shallow-render](https://github.com/getsaf/shallow-render) - Angular testing made easy with shallow rendering and easy mocking.
+* [@storybookjs/testing-angular](https://github.com/storybookjs/testing-angular) - Testing utilities that allow you to reuse your stories in your unit tests.
 
 #### Updating