chore: add latest tag to Docker image builds (#536)

* chore: add latest tag to Docker image builds

Also document the image in the installation guide.

* add latest input to docker.yml

.github/workflows/docker.yml

@@ -7,6 +7,12 @@ on:
         description: 'The version of zizmor to build against'
         required: true
 
+      latest:
+        description: 'Whether to tag the image as latest'
+        required: false
+        default: true
+        type: boolean
+
 permissions: {}
 
 env:
@@ -123,6 +129,7 @@ jobs:
           images: "${{ env.ZIZMOR_IMAGE }}"
           tags: |
             type=raw,value=${{ github.event.inputs.version }}
+            typw=raw,value=latest,enable=${{ github.event.inputs.latest }}
 
       - name: Create manifest list and push
         working-directory: ${{ runner.temp }}/digests

docs/installation.md

@@ -49,6 +49,14 @@ description: Installation instructions for zizmor.
     uvx zizmor --help
     ```
 
+=== ":simple-docker: Docker"
+
+    An official `zizmor` image is available from the [GitHub Container Registry](https://ghcr.io/woodruffw/zizmor):
+
+    ```bash
+    docker pull ghcr.io/woodruffw/zizmor:latest
+    ```
+
 === ":simple-anaconda: Conda"
 
     [![Anaconda-Server Badge](https://anaconda.org/conda-forge/zizmor/badges/version.svg)](https://anaconda.org/conda-forge/zizmor)
@@ -98,7 +106,6 @@ description: Installation instructions for zizmor.
     pacman -S zizmor
     ```
 
-
 === "Other ecosystems"
 
     !!! info