text: Title: Move to a single source of truth for docs — Remove duplicate info from readme
  Body: autogpt_platform\\backend\\README.advanced.md and autogpt_platform\\backend\\README.md. We should just point people to the docs directory (docs/platform/advanced_setup|getting-started) in these. Check the content is all in that file, and the normal getting started, then remove these two files and replace with a link to the docs site — the dev-docs.agpt.co and docs.agpt.co. Call out both and their branch match for released master vs dev branch