docs: fix review gate README anchor

[CooperSheroy]

Summary

• update the README Codex resume section to link to the existing review gate heading
• add a command-docs regression assertion so the stale anchor does not return

Verification

• node --test tests/commands.test.mjs
• git diff --check
• node -e README anchor check for #enabling-review-gate

Note: an initial full npm test run was stopped after it appeared stuck after test 77; all emitted tests up to that point had passed. The focused docs test above passed after the change.

[rajpratham1]

This is a straightforward documentation fix with an appropriate regression test.

Review
README fix ✅

The link changes from:

stop gate

to

review gate

This fixes a broken internal anchor and also updates the terminology to match the current documentation.

Regression test ✅

The added assertions verify both:

the new anchor exists
assert.match(readme, /[review gate](#enabling-review-gate)/i);
the old broken anchor is gone
assert.doesNotMatch(readme, /#what-does-the-review-gate-do/i);

This prevents future documentation regressions.

Risk

None.

Only documentation and a documentation validation test are modified.