add docker build action

.github/workflows/docker.yml

@@ -0,0 +1,29 @@
+name: docker
+
+on:
+  push:
+    branches:
+      - 'main'
+
+jobs:
+  build-and-publish:
+    name: Build & Publish
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@main
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image to ghcr.io
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: ghcr.io/marconlp/snapify:latest