Simplify release guide and add changelog example

Author: Jaysce

RELEASING.md

@@ -0,0 +1,29 @@
+# Releasing Spaceman
+
+Use these steps for a normal release.
+
+## Release steps
+
+1. Choose a semantic version `X.Y.Z`.
+2. Update `MARKETING_VERSION` and `CURRENT_PROJECT_VERSION` in Xcode to `X.Y.Z`.
+3. Update `CHANGELOG.md` with a new section for this version.
+4. Merge to `main`.
+5. Tag that `main` commit as `vX.Y.Z` and push the tag.
+6. The Release workflow will build, sign, generate appcast entries, and publish assets to GitHub Releases.
+
+### Example changelog edit
+
+```md
+## [1.1.0] - 2026-02-06
+
+### Added
+- Added automatic update publishing to GitHub Releases.
+
+### Changed
+- Updated Sparkle integration and release automation scripts.
+```
+
+The heading version must match the app version and tag:
+- `MARKETING_VERSION = 1.1.0`
+- `CURRENT_PROJECT_VERSION = 1.1.0`
+- Git tag: `v1.1.0`