Rewrite CLI reference with all 46 commands and full options

- Add 7 missing commands: action, alerts, group, groups, note, notes, scopes
- Add full option blocks for 18 previously stub commands (ack, close,
  unack, shelve, unshelve, tag, untag, update, delete, watch, raw,
  query, blackout, blackouts, key, user, perm, customer)
- Add common alert selection options pattern (--ids/--query/--filter)
- Fix pingfederate_url -> cas_server in config example
- Update version example from 6.0.0 to 8.5.3
- Fix GitHub links to python-alerta-client repo
- Fix RST title underlines and broken cross-reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: satterly