Update cross-compile documentation

Also, add initial CI test

.gitignore

@@ -1,3 +1,5 @@
 /target
 /logs
-/output
+/output
+.cargo
+.rustup

.woodpecker.yml

@@ -0,0 +1,19 @@
+pipeline:
+  build:
+    image: rust:bookworm
+    commands:
+      - cargo check
+      - apt update && apt install -y lld
+      - cargo build --release --target aarch64-unknown-linux-musl
+  publish:
+    image: woodpeckerci/plugin-gitea-release
+    settings:
+      base_url: https://git.blizzard.systems
+      files:
+        - "target/aarch64-unknown-linux-musl/release/seymour_life"
+      api_key:
+        from_secret: API_KEY
+      target: devel
+      draft: true
+      prerelease: true
+      title: 

README.md

@@ -47,7 +47,7 @@ You can also build without the `--release` flag, which wil take less time, but w
 
 Cross compilation is possible with this project, if you do not have a Raspberry Pi available specifically for compilation. Compilation directly on the Pi is rather intensive, and takes significantly longer than cross-compiling. 
 
-If you are compiling on Linux, cross-compilation has a dependency of `lld`. This can be found in your distribution's package manager, or directly distributed by LLVM. 
+If you are compiling on Linux, cross-compilation has a dependency of `lld`. This can be found in your distribution's package manager, or directly distributed by LLVM. For Nix users, a predefined `shell.nix` file has been provided for your convenience.
 
 If you are compiling on Windows, to safely cross-compile, you must modify the `.cargo/config.toml` file. Replace `lld` with `rust-lld`, then cross-compilation should work properly.
 

shell.nix

@@ -1,4 +1,15 @@
 {pkgs ? import <nixpkgs> {} }:
-  pkgs.mkShell {
-    nativeBuildInputs = with pkgs; [ cargo rustc ];
+  pkgs.mkShell rec {
+    buildInputs = with pkgs; [ lld rustup ];
+    RUSTUP_HOME = toString ./.rustup;
+    CARGO_HOME = toString ./.cargo;
+    RUSTUP_TOOLCHAIN = "stable";
+    HOST_ARCH = "x86_64-unknown-linux-gnu";
+    CARGO_BUILD_TARGET = "aarch64-unknown-linux-musl";
+    shellHook = ''
+      export PATH=$PATH:${CARGO_HOME}/bin
+      export PATH=$PATH:${RUSTUP_HOME}/toolchains/${RUSTUP_TOOLCHAIN}-${HOST_ARCH}/bin/
+
+      rustup target add "${CARGO_BUILD_TARGET}"
+      '';
 }