docs(skills): state that no channel verb creates an integration

The channel card documents `--plugin-ids` as "IDs of plugins (integrations)
subscribed to this channel" without saying where those integrations come
from. Read as a capability claim, it implies the CLI can set an integration
up — so a "how do I connect my mailbox" question turns into an exhaustive
walk of the command tree (`webhook --help`, `datasource --help`,
`__dump-commands` plus several jq passes) that can only ever conclude the
verb is absent.

It is absent by design: creating an integration and reading its inbound
address or token are console-side operations, outside the open API this CLI
speaks. Say so on the card, next to the flag that suggests otherwise, and
point such questions at the product documentation instead.

Author: ysyneu

skills/flashduty/reference/channel.md

@@ -111,4 +111,5 @@ Escalation, silence, inhibit and unsubscribe rules live on their own cards: `ref
 
 - **`channel-id` can be passed positionally or via `--channel-id` — both work** on every verb of this card (`info`, `infos`, `update`, `delete`, `disable`, `enable`). The fence heading `### verb <channel-id>` shows the shorter positional form; the flag is an equally valid alternative, and if both are given the flag value wins.
 - **`channel create` requires `--channel-name` and `--team-id`** even though they are not marked `required` in the flag list — the server rejects the request without them.
+- **`--plugin-ids` subscribes integrations that already exist; no `fduty` verb creates or configures one.** Creating an integration (email, webhook, an alert source) and reading its inbound address/token live in the console only — they are not part of the open API this CLI speaks, so they are absent from the command tree by design. When the user asks how to *connect* something, answer from the product documentation and point at the console; do not dump and grep the command tree looking for a verb that cannot exist. `channel info` likewise reports the channel's own fields, not integration credentials.
 - **`delete` on a channel is irreversible** — all rules within it (escalation, silence, inhibit, drop) are also removed. Confirm the `channel-id` against `list` before proceeding.