The installed-release section of docs/mcp.md said how to register the
server but not how to start an installed app for a live session; the
only start command in the setup steps was the cargo run from a
checkout.
It now gives the command that starts the installed app with
--control 7979 on macOS, Windows and Linux, and says that the
launchers open no control port, that the flagless server checks for
the app once when it starts, and what --connect prints when no app
is listening.