docs: v5.1.0 changelog + Distribution & Updates section

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to markdown-converter will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [5.1.0] - 2026-06-08
+
+### Added
+- Auto-update via electron-updater against GitHub Releases (default) or ConcreteInfo self-hosted feed.
+- Light, skippable first-run wizard: theme, update channel, starter template.
+- One-shot v4.4.1 → v5 settings migration with backup at `settings.v4.bak.json`.
+- Local crash dump capture (cap 20, auto-prune) and a CrashReportModal.
+- "Updates" section in Settings: channel picker, Check now, auto-check toggle.
+
 ## [5.0.0] - 2026-06-06
 
 ### Added

README.md

@@ -140,6 +140,21 @@ Open PDF files directly in MarkdownConverter:
 - Rotate pages left or right
 - Close PDF to return to editor
 
+## Distribution & Updates
+
+v5.x uses `electron-updater` against two feeds:
+
+- **GitHub Releases** (default, public): the public release at `https://github.com/amitwh/markdown-converter/releases`. The CI workflow publishes `latest-{mac,linux,windows}.yml` on every tag.
+- **ConcreteInfo self-hosted** (opt-in for enterprise deployments): `https://updates.concreteinfo.co.in/v5/`. CI mirrors artifacts on every release when `CONCRETEINFO_DEPLOY_HOOK` is set as a repository secret.
+
+Users switch the feed in **Settings → Updates → Update channel**. Auto-check is enabled by default; disable it in the same panel.
+
+### Manual mirror
+
+```bash
+CONCRETEINFO_DEPLOY_HOOK=... npm run publish:concreteinfo -- 5.1.0
+```
+
 ## Open Source
 
 MarkdownConverter is 100% open-source. All dependencies are permissively licensed: