docs: expert-adcp-reviewer.md still references D1–D21 (now D1–D24) #44

.github/ai-review/expert-adcp-reviewer.md says D1–D21 in two places:

• line 9 — "ROADMAP.md §Confirmed decisions — D1–D21 lock in architecture, build, and conventions..."
• line 138 — "Walk the relevant Confirmed Decisions in ROADMAP.md (D1–D21) and check the diff doesn't drift any of them."

ROADMAP.md has carried D1–D24 since D22–D24 landed. This matters more than the same typo elsewhere: that file is the Argus review prompt, so the reviewer is told to check a decision range that stops three rows short — D22 (multi-tenant signing keys), D23 (AdCP 3.1 beta parity target) and D24 (agent response size cap) are outside the range it is instructed to walk.

The equivalent stale counts in CONTRIBUTING.md and CLAUDE.md were fixed in #43. This file was deliberately left out of that PR: it is a self-modification guarded path, so touching it would have paused Argus and defeated that PR's purpose as the end-to-end proof for #41.

Fixing it needs its own PR with a human reviewer, since Argus will pause on it by design.

Raised by Argus in its reviews of #43 (#43 (review)).