Add release workflow and docs

docs/RELEASING.md

@@ -0,0 +1,21 @@
+# Releasing
+
+This repo includes a Gitea Actions workflow that builds Linux binaries for
+`x86_64` and `arm64` and uploads them to the release.
+
+## One-time setup (Gitea Actions)
+1) Create a personal access token with repo write access.
+2) Add it to the repo secrets as `GITEA_TOKEN`.
+
+## Release steps
+1) Update `CHANGELOG.md`.
+2) Create and push a tag:
+   ```bash
+   git tag -a vX.Y.Z -m "vX.Y.Z"
+   git push origin vX.Y.Z
+   ```
+3) The workflow builds and uploads binaries to the release.
+
+## Artifacts
+- `mov-renamarr-<tag>-x86_64-linux-gnu.tar.gz`
+- `mov-renamarr-<tag>-arm64-linux-gnu.tar.gz`