Documentation corrections: dependency requirements and AI module version
## Problem
Follow-up to:
#3586294+s
Parent:
#3586310+s
_**This issue should be verified prior to working on it to make sure it is valid.**_
Two user-facing doc errors beta testers will hit:
- `docs/index.md` lists Scheduler and Scheduler Content Moderation Integration as **required**; `README.md` and `composer.json` (require-dev) treat them as optional, and the code degrades gracefully without them.
- `README.md` states AI module `^1.3.4`; `composer.json` requires `drupal/ai ^1.4 || ^2`.
## Proposed resolution
Fix `docs/index.md` to mark both modules optional and correct the README version string.
## AI usage
- [x] AI assisted issue
issue