README improvements for apps

Retool has released several improvements to the README experience for web apps:

• The README is now located at the top of the Pages or Screens list for easy access.
• You can now use AI to generate a README automatically based on the components and logic of your app.

Previously, app READMEs were found by clicking the title of the app. If your app has an existing README, you can now find it in the Pages tab.