Document unambiguous literal-instruction routing in CLI help #729

Summary

The advertised maco <instruction> entrypoint needs a leading -- escape when the first word matches a subcommand or starts like an option, but that escape is absent from onboarding and top-level help.

Evidence and reproduction

On main fa0c79b9ae38eca2c59b2b1911becfe1a6b3c9ab, README.md:180-183,3902-3905 presents the bare entrypoint. src/cli.rs:133-142,153-181 preserves explicit subcommands/options and only forces literal routing when the first argument is --. Thus a sentence beginning with review, merge, repo or issue enters command parsing instead of becoming a literal task.

tests/cli_smoke.rs:161-170 checks top-level Usage: maco <COMMAND>, and lines 213-224 verify the working forced-instruction escape. The parser contract already supports a remedy; it is undiscoverable where users start.

Acceptance criteria

• Explain maco -- <instruction> beside the bare entrypoint introduction and in top-level help, including a concrete subcommand-word example.
• Document that literal routing is a live supervised launch so users understand its effect.
• Add a help/onboarding regression without changing explicit command semantics.
• An explicit unambiguous instruction command is an alternative only if justified; the existing escape is sufficient for the minimal correction.

Verification and related work

Source/test-definition inspection only; no provider was launched. Closed #555/#559 addressed other entrypoint/docs inconsistencies. No open Issue/PR covers this escape/help gap.