docs: drop refs to removed mo check/doctor and missing perf_baseline.sh

mo check / mo doctor were removed in a prior release but the Command Surface
section still listed them; release-pitfalls note at line ~184 stays as a
historical lesson about verifying every documented command exists in HEAD.

Repository Map still claimed scripts/perf_baseline.sh; that file does not
exist. Per-PR perf is covered by tests/core_performance.bats.