add overview arch map and workthrough section (#102)

## Purpose

docs refine

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[x] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:
```

Author: sonwan2020

images/acalab-overview.png

@@ -6,7 +6,7 @@ nav_order: 1
 
 # Lab: Deploying and running Java Applications in Azure Container Apps
 
-This lab teaches you how to deploy the [Spring Petclinic Microservices](https://github.com/Azure-Samples/java-microservices-aca-lab/tree/main/src) application to an Container Apps environment and integrate it with additional Azure services.
+This lab teaches you how to deploy the [Spring Petclinic Microservices](https://github.com/Azure-Samples/java-microservices-aca-lab/tree/main/src) application with OpenAI to an Azure Container Apps environment and integrate it with additional Azure services, also some samples for Azure Container Apps features.
 
 ## Modules
 
@@ -19,6 +19,9 @@ This lab has modules on:
 * Build intelligent Spring Apps with Azure OpenAI
 * Protect endpoints using Web Application Firewalls
 * Secure MySQL database and Key Vault using a Private Endpoint
+* Messaging between microservices
+* Build reliable java apps on Azure Container Apps
+* Set up autoscaling for microservices on Azure Container Apps
 
 The lab is available as GitHub pages [here](https://azure-samples.github.io/java-microservices-aca-lab/)
 
@@ -31,6 +34,34 @@ For running this lab you will need:
 * A GitHub account
 * An Azure Subscription
 
+### Workthrough guide
+
+Based on your current knowledge background and your plan, there are some typical usage scenarios for your reference:
+
+* If you are not familiar with Azure Spring Apps and want to learn how to deploy new project in Azure Container Apps, you may start from these labs:
+  * [Lab 2: Migrate a Spring Apps microservices application to Azure Container Apps]({% link docs/02_lab_migrate/02_openlab_setup_aca.md %})
+  * [Lab 3: Enable monitoring and end-to-end tracing]({% link docs/03_lab_monitor/03_openlab_monitoring_aca.md %})
+  * [Lab 4: Connect to Database securely using identity]({% link docs/04_lab_secrets/04_openlab_secrets_aca.md %})
+
+  It will take about 2 days to learn from these labs
+
+* If you already have some experiences on Azure Container Apps, and you want to try some azd automation to get a AI enabled microservice environment, you may jump directly to
+  * [lab 6: Deploy to Azure automatically]({% link docs/06_lab_automation/06_openlab_automation.md %})
+
+  You may get a new environment in 2 hours.
+
+* If you want to learn how AI components are integrated in to microservices, you may check the details in
+  * [Lab 5: Integrate with Azure OpenAI]({% link docs/05_lab_openai/05_openlab_openai_aca.md %})
+
+* If you need a more secure app environment, refer to
+  * [Lab 7: Protect endpoints using Web Application Firewall]({% link docs/07_lab_security/07_openlab_security_aca.md %})
+  * [Lab 8: Secure MySQL database and Key Vault using a Private Endpoint]({% link docs/08_lab_private/08_openlab_private_endpoints_aca.md %})
+
+* There are also some useful features in Azure Container Apps, you may find your interested topics in:
+  * [Lab 9: Create and configure Azure Service Bus for sending messages between microservices]({% link docs/09_lab_messaging/09_openlab_messaging_aca.md %})
+  * [Lab 10: Build reliable Java application on ACA]({% link docs/10_lab_reliable_application/10_reliable_java_aca.md %})
+  * [Lab 11: Set up autoscaling for microservices on ACA]({% docs/11_lab_scale/11_openlab_scale_aca.md %})
+
 ### Installation
 
 For running this lab with all the needed tooling, there are 3 options available: