chore: update contributing

CONTRIBUTING.md

@@ -7,3 +7,19 @@ This projects requires you to have Node.js (with npm) and Composer.
 - You can run `npm ci` & `composer install` to install dependencies.
 - Once done, you can run `npm run build` to generate build files.
 - You can also use `npm run dev` to generate dev build if you are working on the files.
+
+> [!NOTE]  
+> The minimum Node version is 16. The version recommended is 18 or higher (tested up to 21). For PHP, use 7.4.
+
+## E2E Testing
+
+We use Playwright to write the E2E together with WordPress tool set.
+
+Use `npm run wp-env start` to start the testing environment.
+
+> [!NOTE]  
+> The testing instance has a port that need to be free to work with setup (usually the port 8889).
+
+Install Playwright with `npm install -g playwright-cli` and `npx playwright install`.
+
+Use `npm run test:e2e:playwright:ui` to lunch it in UI mode for easy development.