feat(ui-test): improve readme (#1690)

apps/laboratory/tests/README.md

@@ -1,3 +1,15 @@
-# Debugging
+# Functional Tests
+
+We use Playwright as our functional test runner. It's configured to try multiple permutations:
+
+- Browsers: Chromium/Firefox
+- Modal flavors: default/SIWE/email
+
+## Running Tests
+
+- `npx playwright test` to run in default mode (make sure your `.env` is set up)
+- `npm run playwright:debug` to step by step see what the tests are doing
+
+## Debugging
 
 For scenarios when tests pass locally but not remotely you can `await this.page.screenshot({ path: './screenshots/wallet.png' })` and the screenshot will be uploaded to GitHub Actions.