docs: the release procedure never mentioned the Homebrew tap it publishes

[skyoo2003]

Summary

The release process lived at docs/release.md and covered the tag pipeline end to end except for what it hands to a second repository. This moves it to RELEASE.md at the repo root and closes three gaps against the files that actually define the pipeline.

Related Issue

N/A — no tracking issue. The Changie fragment references this PR number, following the convention in Documentation-20260906-210200.yaml (#147) and Documentation-20260906-100200.yaml (#144).

Changes

Documented what was missing — each row was read out of the config, not recalled:

Gap	Source of truth	What the doc said before
Homebrew tap publishing	.goreleaser.yaml:67-82, release.yml:252-260	nothing at all
Four *-alpine tags per release	.goreleaser.yaml:93-97	"versioned *-alpine container images"
make changelog VERSION=	Makefile:31-36	the two changie commands, by hand
Notes heading must name this tag	release.yml:198-209	"verify the file exists"
dry_run defaults to true	release.yml:17	unstated
Example version v1.1.0	changes/v1.0.0.md shipped	v0.3.0, three releases stale

The Homebrew gap is the one with teeth: a maintainer debugging a failed release had nothing telling them the formula step needs a GitHub App still installed on the tap, with unexpired TAP_APP_ID / TAP_APP_PRIVATE_KEY.

Moved the file and repointed everything at it — docs/release.md → RELEASE.md, beside the other governance files. Four inbound links updated (CONTRIBUTING.md, docs/README.md, docs/compatibility-policy.md, .github/pull_request_template.md), and the file's own seven relative links rewritten for the root.

Added RELEASE.md to the archive files list in .goreleaser.yaml. The docs/ tree ships whole but root files are enumerated one by one, so moving the file out of docs/ without this leaves docs/README.md pointing at nothing inside the tarball — the same dangling-link failure the comment above that list already records.

Files Changed

File	Change
docs/release.md → RELEASE.md	Renamed + content refresh (89 lines)
.goreleaser.yaml	Modified — RELEASE.md added to archives[0].files
CONTRIBUTING.md	Modified — link
docs/README.md	Modified — link
docs/compatibility-policy.md	Modified — link
.github/pull_request_template.md	Modified — link
changes/unreleased/Documentation-20260906-220000.yaml	Added

Docs and config only. No Go source, no tests, no generated code.

Test Plan

• Every relative link in RELEASE.md resolves from the repo root — extracted all seven targets and stat'd each: .changie.yaml, .goreleaser.yaml, .github/workflows/release.yml, .github/workflows/cd.yml, CHANGELOG.md, docs/compatibility-policy.md, internal/config/config.go. All present.
• No stale docs/release.md reference survives in live docs — grep -rn 'docs/release\.md' over *.md/*.yml/*.yaml returns only .claude/plans/*.plan.md, historical planning records left as written.
• Pre-commit passed — yaml check covers the new Changie fragment; the Go and ruff hooks had no files to act on.
• Not run: the Go suite and the boto3 compatibility suite. Nothing in this diff reaches either.

The .goreleaser.yaml edit is the one change with a runtime effect, and it is only verifiable at release time — a dry run (Release → Run workflow, dry_run: true) would confirm RELEASE.md lands in the archive.

Checklist

• Self-reviewed the code
• Added/updated tests — N/A, docs and config only
• Lint/format passes (pre-commit hooks green; golangci-lint N/A, no Go changed)
• Updated documentation (if applicable)
• Added a Changie changelog fragment for user-facing changes (changie new, see RELEASE.md)