The Slack docs jumped straight from intro into the Quick Setup tabs
without telling readers when to pick each transport. Add a Choosing
Socket Mode or HTTP Request URLs section above Quick Setup with a
concern-by-concern table (public URL, outbound network, tokens, dev
laptops, scaling, multi-account, slash command transport, signing,
recovery) plus a Note pointing at the right default for each shape.
Also add an Info block under the HTTP Quick Setup manifest explaining
why the manifest carries three url fields (slash_commands[].url,
event_subscriptions.request_url, interactivity.request_url) — Slack's
manifest schema requires them spelled out separately even though
OpenClaw routes by payload type, and slash commands silently no-op
without their url field in HTTP mode.