Fix for failing docker build task

The docker build task docker build --tag $ACR_NAME.azurecr.io/albumapp-ui . is failing because of missing quotes. Proposing a change to include the quotes:
docker build --tag "$ACR_NAME.azurecr.io/albumapp-ui" .

Author: owingruters

articles/container-apps/communicate-between-microservices.md

@@ -129,13 +129,13 @@ Output from the `az acr build` command shows the upload progress of the source c
     # [Bash](#tab/bash)
 
     ```azurecli
-    docker build --tag $ACR_NAME.azurecr.io/albumapp-ui . 
+    docker build --tag "$ACR_NAME.azurecr.io/albumapp-ui" . 
     ```
 
     # [PowerShell](#tab/powershell)
 
     ```powershell
-    docker build --tag $ACR_NAME.azurecr.io/albumapp-ui . 
+    docker build --tag "$ACR_NAME.azurecr.io/albumapp-ui" . 
     ```
 
     ---
@@ -283,4 +283,4 @@ az group delete --name $RESOURCE_GROUP
 ## Next steps
 
 > [!div class="nextstepaction"]
-> [Environments in Azure Container Apps](environment.md)
+> [Environments in Azure Container Apps](environment.md)