update readme

Author: s1gr1d

README.md

@@ -5,3 +5,27 @@ _This repository is a work in progress_
 The main purpose of this repository is to visualize the differences between the
 [Sentry JS SDK](https://github.com/getsentry/sentry-javascript) version 7 and version 8. Those
 example applications can also be used as a reference for using the JS SDKs.
+
+## How to test apps and save the payloads
+
+1. Change the `APP` variable of `utils/event-proxy-server/src/event-proxy-server.ts` to the app
+   folder name you want to test.
+   - Example: `apps/express` -> `APP = 'express'`
+2. Make sure you have a folder named like the app in `utils/event-proxy-server/payload-files`.
+   - Example: `apps/express` -> `utils/event-proxy-server/payload-files/express`
+3. Run `yarn start:proxy-server`.
+4. Run `yarn start:[app]` like `start:express`.
+5. Check the "Disable Cache" option in the DevTools Network tab of your browser.
+6. Open the following URLs in your browser.
+7. The json file will be generated.
+
+### Test URLs
+
+- http://localhost:3030/test-success
+- http://localhost:3030/test-error
+- http://localhost:3030/test-param-success/1337
+- http://localhost:3030/test-param-error/1337
+- http://localhost:3030/test-success-manual
+- http://localhost:3030/test-error-manual
+- http://localhost:3030/test-local-variables-caught
+- http://localhost:3030/test-local-variables-uncaught