Add cleanup, add usage and readme, update build schedule

.github/workflows/build-push.yml

@@ -9,7 +9,7 @@ on:
     branches:
       - main
   schedule:
-    - cron: '15 2 * * SUN'
+    - cron: '30 2 * * SUN'
 
 jobs:
   build-and-push:

.github/workflows/container-cleanup.yml

@@ -0,0 +1,16 @@
+name: Container Registry Cleanup
+
+permissions:
+  contents: read
+  packages: write
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '30 2 * * MON'
+
+jobs:
+  untagged-cleanup:
+    uses: "tweedegolf/actions-container-helpers/.github/workflows/container-untagged-cleanup.yml@main"
+    with:
+        package: rust-dev

README.md

@@ -1 +1,42 @@
 # Rust development Docker images
+This development image contains a Rust compiler toolchain and a C/C++ compiler
+toolchain. It also includes debugging and analysis tools such as lldb, gdb and
+valgrind. This image is intended for development only. For production use-cases
+you should just start with the base debian image and add your compiled binaries
+to it (and install any optional library dependencies). Currently these versions
+are supported:
+
+* Rust stable: `stable` (`ghcr.io/tweedegolf/rust-dev:stable`)
+* Rust 1.77: `1.77`, `latest` (`ghcr.io/tweedegolf/rust-dev:1.77`)
+* Rust 1.76: `1.76` (`ghcr.io/tweedegolf/rust-dev:1.76`)
+* Rust beta: `beta` (`ghcr.io/tweedegolf/rust-dev:beta`)
+* Rust nightly: `nightly` (`ghcr.io/tweedegolf/rust-dev:nightly`)
+
+Furthermore, each version also has a `-node` variant that includes the latest
+LTS release of node.js and yarn.
+
+## Usage in docker compose
+
+```yaml
+services:
+    # ...
+    app:
+        image: ghcr.io/tweedegolf/rust-dev:stable
+        # You will have to define the USER_ID and GROUP_ID environment variables
+        # as `export USER_ID=$(id -u)` and `export GROUP_ID=$(id -g)` if they
+        # have not already been defined previously
+        user: "$USER_ID:$GROUP_ID"
+        volumes: [.:/app]
+        # Change to whatever command you wish to use instead of cargo watch
+        command: [cargo, watch, -x, "run"]
+        working_dir: /app
+        environment:
+            # This allows sharing cargo download even across multiple containers
+            CARGO_HOME: ".cargo"
+            # Create a separate target dir inside the container to prevent
+            # waiting for rust-analyzer on your host
+            CARGO_TARGET_DIR: "target-docker"
+        # Optionally define some ports to use externally
+        ports: ["127.0.0.1:8000:8000"]
+
+    # ...