Improve Playwright cheatsheet

test/e2e/playwright_guide/playwright_cheatsheet.md

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+# Playwright Cheatsheet - run and debug tests
+## Most simple
+1. install VSCode Extension: [*Playwright Test for VSCode*](https://marketplace.visualstudio.com/items?itemName=ms-playwright.playwright)
+1. `cd docker`
+1. `make`
+1. run tests directly with the extension in the side bar 
+1. ![Screenshot showing VSCode Playwright extension](playwright_extension_sidebar.png "Playwright Test for VSCode")
+1. or run tests directly from the spec files
+
+![Screenshot showing extension in the file](playwright_extension_in_test_file.png)
+### Debug tests
+- debug tests by setting breakpoints in VSCode and select (right click on green triangle) *Debug Test*
+## Simple
+1. `cd docker`
+1. `make playwright-tests`
+This commands executes the playwright tests. Execution is specified in the makefile.
+## More options
+### Setup
+1. `cd docker`
+1. `make`
+1. `cd ..`
+1. `npx playwright test`
+### Options
+- run only a specific test file: `npx playwright test project.spec.ts`
+- run only a specific test: add `.only` to the test
+![Screenshot showing how to add .only to a test](debugging_dot_only.png)
+    - only tests which have the `.only` will be executed (one can add `.only` to multiple tests)
+- view how the tests are run: `npx playwright test --headed`
+- step through the single lines, clicking *next* : `npx playwright test --debug`
+
+## Essential to know
+1. delete all *storageState.json* files before running the tests: `rm *storageState*`
+1. not all tests will be executed but Playwright will indicate how many were executed or skipped, e.g., *4 skipped*, *50 passed*. Tests are skipped when they are ought to be skipped (see screenshot below, `.skip`) or when something goes wrong, e.g. an error in the beforeAll leads to all tests of this block being skipped.
+
+![Screenshot showing how to add .skip to a test](debugging_dot_skip.png)