added deploying a docker image to docker hub

.circleci/config.yml

@@ -26,9 +26,32 @@ jobs:
                   name: Test Frontend
                   command: |
                       npm test
+    build_docker_image:
+        docker:
+            - image: circleci/node:14
+
+        working_directory: ~/app
+
+        steps:
+            - checkout
+            - run:
+                  name: Build Docker Image
+                  command: |
+                      docker build -t $DOCKER_HUB_USERNAME/mern-ludo:latest .
+            - run:
+                  name: Push Docker Image
+                  command: |
+                      echo "$DOCKER_HUB_PASSWORD" | docker login -u "$DOCKER_HUB_USERNAME" --password-stdin
+                      docker push $DOCKER_HUB_USERNAME/mern-ludo:latest
+        
+
 
 workflows:
     version: 2
     build:
         jobs:
             - build_and_test
+            - build_docker_image:
+                filters:
+                    branches:
+                        only: main