docs: move community presets from README to docs/community (#2314)

Move the community presets table from the main README to a dedicated
docs/community/presets.md page, matching the pattern used for
walkthroughs and friends.

- Add docs/community/presets.md with the full presets table
- Add Claude AskUserQuestion preset (was in catalog but missing from table)
- Add Presets entry to docs/toc.yml under Community
- Replace inline README table with a short link to the docs page