cleanup is called now by default after each test if the testing framework supports the afterEach global

* Adopt Contributor Covenant

* Add link to Contributor Covenant to docs site

- use ESLint cache
- remove useless `watch` option in fork-ts-checker

Add blog post that takes a React developer step-by-step through many features of AWS. Blog post is suitable for a beginner to follow and have a production ready workflow.

 - babel-plugin-named-asset-import@0.3.4
 - babel-preset-react-app@9.0.2
 - confusing-browser-globals@1.0.9
 - create-react-app@3.1.2
 - eslint-config-react-app@5.0.2
 - react-app-polyfill@1.0.3
 - react-dev-utils@9.0.4
 - react-error-overlay@6.0.2
 - react-scripts@3.1.2

Closes #7741

typo fix

* Add header to checkValidServiceWorker (ts)

* Add header to checkValidServiceWorker

* Add additional information for postcss errors

* Add additional information for postcss errors (simplify)

* Remove chunkname from postCSS compile error

* Remove line number from postCSS compile error

* Add Alex to lint documentation

* Attempt to trigger GitHub Action

* Configure Alex and update docs

* More docs updates

* Add template support

* Update templates version check

* Update TypeScript template README

Rebased again now with smaller changes in this one which will make it easier to revert in case of eventual regressions.