Explain how to run over SSH

Signed-off-by: Lukasz Gryglicki <[email protected]>

Assisted by [OpenAI](https://platform.openai.com/)

Assisted by [GitHub Copilot](https://github.com/features/copilot)

Author: lukaszgryglicki

tests/functional/README.md

@@ -88,7 +88,7 @@ CYPRESS_ENV=dev
 You can ask for example `.env` file over slack.
 
 - Run `npx cypress install`
-- Run tests using cmd `npx cypress run`.
+- Run tests using cmd `npx cypress run`. Or `xvfb-run -a npx cypress run` when runnign over SSH.
 - Run tests using UI `npx cypress open`. Choose **E2E testing**, select **Chrome** browser.
 - View test reports in the `cypress-report` directory.
 - Explore source code files for detailed implementation.