Add some comments for readability.

.github/workflows/dockerhub.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
 
-      - name: Test image
+      - name: Test image # Checks we are able to run the container.
         run: docker compose -f docker-compose.test.yml run sut
 
   build:

docker-compose.test.yml

@@ -1,3 +1,4 @@
+# This is used by Github actions to ensure docker images build properly.
 version: "3.9"
 
 services:

docker-compose.yml

@@ -1,3 +1,5 @@
+# This is an example. Please change the configuration variables listed here.
+
 version: "3.9"
 
 services: