docs: add packaging instructions (#868)

PACKAGING.md

@@ -1,3 +1,50 @@
 ## Packaging Fish Folk: Jumpy
 
-TODO: Rewrite for Bevy refactor.
+### Dependencies
+
+See [Bevy dependencies](https://github.com/bevyengine/bevy/blob/main/docs/linux_dependencies.md).
+
+#### Build dependencies
+
+- [Rust](https://www.rust-lang.org/tools/install)
+- [libudev](https://www.freedesktop.org/software/systemd/man/libudev.html)
+
+#### Runtime dependencies
+
+- [Mesa](https://www.mesa3d.org/) - [OpenGL](https://www.opengl.org) (`3.2+`)
+- [alsa-lib](https://github.com/alsa-project/alsa-lib)
+
+### Build
+
+```sh
+# export CARGO_TARGET_DIR=target
+cargo run --release --locked
+```
+
+### Environment variables
+
+- `JUMPY_ASSETS`: assets directory (default: `assets/`)
+- `JUMPY_ASSET_PACKS`: mods directory (default: `packs/`)
+
+### Package
+
+Binary will be located at `target/release/jumpy` after [build](#build). To run it, `assets` directory should be placed in the same directory or a path can be specified via `JUMPY_ASSETS` environment variable.
+
+For example:
+
+```sh
+export JUMPY_ASSETS=/opt/jumpy/assets/
+target/release/jumpy
+```
+
+The desktop file in the contrib/ directory can be installed to allow running the game from your desktop's app launcher.
+
+Also see [README.md#distro-packages](./README.md#distro-packages)
+
+### Binary releases
+
+Binary releases are automated via [Continuous Deployment](./.github/workflows/release.yml) workflow and they can be downloaded from the [releases](https://github.com/fishfolks/jumpy/releases) page. Release artifacts are named in the following format:
+
+- `jumpy-<version>-<target>.<ext>`
+
+A single archive includes the `jumpy` binary and `assets` directory. It can be verified by using a SHA256 hash file that has the same name as the artifact except it ends with ".sha256". Release artifacts are not signed at this time.