ci: Separate docker hub updates into separate workflow

Allows updating the README outside of Docker image releases.

.github/workflows/docker-hub.yml

@@ -0,0 +1,24 @@
+# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json
+name: Docker Hub Updates
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - README.md
+      - .github/workflows/docker-hub.yml
+  workflow_dispatch:
+
+jobs:
+  readme:
+    name: Update Repo Metadata
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Update Docker Hub Description
+        uses: peter-evans/dockerhub-description@v3
+        if: github.ref == 'refs/heads/master'
+        env:
+          DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+          DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_TOKEN }}
+          DOCKERHUB_REPOSITORY: ${{ github.repository }}

.github/workflows/docker.yml

@@ -73,11 +73,3 @@ jobs:
           platforms: linux/arm/v7,linux/arm64,linux/amd64
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-
-      - name: Update Docker Hub Description
-        uses: peter-evans/dockerhub-description@v3
-        if: github.ref == 'refs/heads/master'
-        env:
-          DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
-          DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_TOKEN }}
-          DOCKERHUB_REPOSITORY: ${{ github.repository }}