chore: Updated README E2E Testing Instructions

Updated the instructions for E2E testing

- Cypress was removed and replaced with playwright (https://github.com/logseq/logseq/pull/3241)
- Instructions are based on @andelf comment (https://github.com/logseq/logseq/pull/3241#issuecomment-976201958)

README.md

@@ -112,12 +112,15 @@ Run ClojureScript tests
 yarn test
 ```
 
-Run Cypress tests
+Run E2E tests
 
 ``` bash
-yarn e2e-test
+yarn electron-watch
+# in another shell
+yarn e2e-test # or npx playwright test
 ```
 
+
 ## Desktop app development
 
 ### 1. Compile to JavaScript