Missed one API subdir

Author: ch-rob

docs/aca/01-deploy-api-to-aca/index.md

@@ -178,7 +178,7 @@ We will be using Azure CLI to deploy the Web API Backend to ACA as shown in the
 
     ```shell
     cd ~\TasksTracker.ContainerApps
-    az acr build --registry $ACR_NAME --image "tasksmanager/$BACKEND_API_NAME" --file 'TasksManager.Backend.Api/Dockerfile' .
+    az acr build --registry $ACR_NAME --image "tasksmanager/$BACKEND_API_NAME" --file 'TasksTracker.TasksManager.Backend.Api/Dockerfile' .
     ```
     Once this step is completed you can verify the results by going to the Azure portal and checking that a new repository named `tasksmanager/tasksmanager-backend-api` has been created and there is a new docker image with a `latest` tag is created.