docs: add end to end tests to contributing guide

apps/docs/contributing.mdx

@@ -33,9 +33,10 @@ pnpm install && pnpm dev
 
 5. The backend should now be running locally on `http://localhost:4000`.
 6. Create a new branch for your changes.
-7. Develop your feature or fix and write tests for it.
-8. Commit your changes and push them to your forked repository.
-9. Submit a pull request to the main repository.
+7. Develop your feature or fix and write tests for it. Specifically, writing an end to end test for your feature is highly recommended.
+8. Ensure all tests pass by running `pnpm test:e2e` (you will need to be running the dev server locally on port 4000 with HTTP for this to work)
+9. Commit your changes and push them to your forked repository.
+10. Submit a pull request to the main repository.
 
 ## Improving the Documentation