Update README.md

Author: tobikli

README.md

@@ -8,3 +8,16 @@ Scaled tests run via the Playwright [Artillery](https://artillery.io) Framework
 - Single User Playwright Tests are run using a Test Account for Keycloak, to change the Test User, change the environment variables in GitHub Secrets \
 -> Settings -> Secrets and variables -> Actions -> Secrets -> Repository Secrets \
 or [here](https://github.com/ls1intum/theia-scale-tests/settings/secrets/actions)
+- To run the tests on the deployed Theia instance, simply run:
+  ```
+  npx playwright test
+  ```
+- To run tests locally using a Theia Instance on localhost, change the environment variable to the corresponding port and run the tests using:
+  ```
+  npx playwright test --project=local
+  ```
+- Test files that allow local testing (testing without Landing Page and Keycloak) have the following file ending:
+  ```
+  *.ide.spec.ts
+  ```
+