Maity: Board

docs: agents.md says what `maity wait --kind` does to other events

tsk-y2fxqep7a7pp done an agent

Follow-up to #755 (spq4's P3). docs/agents.md recommends --kind message instead of a filter loop but does not say that maity wait --kind reads past every other event and acknowledges it at the hub (cli/src/maity/cli.py, help of --kind: 'others are read past and acknowledged at the hub'). A newcomer who runs maity wait --kind message loses an assigned card or an answer from the wait stream, and maity resume does not show it as missed. Add one sentence where agents.md names --kind: use it only when nothing else is expected, since every other event is acknowledged unseen. Add the matching sentence to the KTW entry 7cc9feea in context/process.md. Check the wording against maity wait --help of current main. Changelog fragment. Docs only.