improve comments and ghcr username

.github/workflows/docker-build-and-push.yml

@@ -1,6 +1,8 @@
+---
 name: Build and Push Image
 
 on:
+  # we want pull requests so we can build(test) but not push to image registry
   pull_request:
     branches:
       - 'main'
@@ -37,14 +39,17 @@ jobs:
           tags: |
             type=raw,value=latest
       -
+        # we need qemu and buildx so we can build multiple platforms later
         name: Set up QEMU
         id: qemu
         uses: docker/setup-qemu-action@v1
       -
+        # BuildKit (used with `docker buildx`) is the best way to build images
         name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v1
-      -        
+      -
+        # This makes image builds fast!      
         name: Cache Docker layers
         uses: actions/cache@v2
         with:
@@ -65,9 +70,11 @@ jobs:
         uses: docker/login-action@v1
         with:
           registry: ghcr.io
-          username: ${{ github.repository_owner }}
+          username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
       -
+        # this will build the images, once per platform, 
+        # then push to both Docker Hub and GHCR
         name: Build and push
         id: docker_build
         uses: docker/build-push-action@v2