docs(standards): add critical rule 8 — update documentation when changing behavior

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: matthew-on-git

CLAUDE.md

@@ -12,6 +12,7 @@ See DEVELOPMENT.md for the complete reference.
 5. **Write idempotent scripts.** Every script must be safe to re-run. Check before acting: `command -v tool || install_tool`, `mkdir -p`, guard file writes with existence checks.
 6. **Use the shared logging library.** No raw `echo` for status messages. Use `log_info`, `log_warn`, `log_error`, `log_debug`, and `die` from `lib/log.sh`.
 7. **Never suppress failing checks.** When a lint, format, security, or test check fails, fix the underlying issue. Never comment out code, add suppression annotations, disable rules, or mark CI jobs as allowed-to-fail to bypass a failing check.
+8. **Update documentation when changing behavior.** When a change affects public interfaces, configuration, CLI usage, or setup steps, update the relevant documentation (README, DEVELOPMENT.md, inline docs) in the same commit or PR. Do not leave documentation out of sync with code.
 
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