Add the readme for sample app codes, and update the code-sample page (#6059)

* feat: add the readme for sample app codes, and modify the code-sample page to include bookstore app

* fix: fix the wrong link

* fix: add a note box to mention all 3 parts of knative are being convered in bookstore tutorial

code-samples/eventing/bookstore-sample-app/README.md

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+# Knative Bookstore Code Samples
+
+This folder contains code samples for the Knative Bookstore tutorial, an end-to-end sample application demonstrating Knative's capabilities in building an event-driven architecture.
+
+## Tutorial
+
+For a comprehensive guide on building this application and learning about Knative, please visit the [Knative Bookstore Tutorial](https://knative.dev/bookstore/page-0/welcome-knative-bookstore-tutorial/).
+
+This tutorial covers:
+- Setting up your environment
+- Implementing event-driven architecture with Knative
+- Deploying and connecting various microservices
+- Integrating machine learning models
+- Connecting to external services like Slack
+
+Whether you're new to Knative or looking to deepen your understanding, this tutorial provides valuable insights into building scalable, event-driven applications.
+
+## Contents
+
+The files are organized into two main folders:
+
+1. **/start**: Contains the initial code structure and base files to begin the tutorial.
+
+2. **/solution**: Includes the complete, fully implemented version of the Knative Bookstore application.
+
+For more details on the directory structure and contents of each folder, please refer to their respective README files:
+
+- [Start README](start/README.md)
+- [Solution README](solution/README.md)
+
+## Getting Started
+
+1. Clone this repository
+2. Navigate to the `/start` directory to begin the tutorial
+3. Follow the Knative Bookstore Tutorial for step-by-step instructions
+4. Refer to the `/solution` directory if you need to check the final implementation
+
+Happy coding!

code-samples/eventing/bookstore-sample-app/solution/README.md

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+
+# Knative Bookstore Tutorial - Solution Directory
+
+Welcome to the solution directory of the Knative Bookstore tutorial. This directory contains the fully implemented version of the event-driven bookstore application using Knative.
+
+You can find the tutorial for this solution [here](https://knative.dev/bookstore/page-0/welcome-knative-bookstore-tutorial/).
+
+## Directory Structure
+
+Here's an overview of the components in the solution:
+
+- `bad-word-filter/`: Knative Function for filtering out inappropriate content
+- `db-service/`: Database service for storing book reviews and comments
+- `frontend/`: User interface for the bookstore application built with Next.js
+- `node-server/`: Node.js server for handling backend operations
+- `sentiment-analysis-app/`: Knative Function for analyzing the sentiment of book reviews
+- `sequence/`: Knative Sequence setup for orchestrating workflows
+- `slack-sink/`: Integration with Slack for notifications with Apache Camel
+
+## Additional Files
+
+- `setup.sh`: Script for setting up the required services including installing Knative, frontend, and backend node-server
+- `solution.sh`: Script for installing everything, deploying the entire solution. **It includes the setup script as well.**
+
+## Running the Solution
+
+1. Have a running Kubernetes cluster.
+2. Install all the prerequisites and deploy the entire solution using the `solution.sh` script:
+   ```
+   ./solution.sh
+   ```
+If you encountered any permission issues, run the following command:
+   ```
+   chmod +x solution.sh
+   ```
+
+## Next Steps
+
+- Explore each component to understand how they work together in an event-driven architecture.
+- Compare this solution with your own implementation if you've completed the tutorial.
+- Experiment with modifying or extending the solution to add new features.
+
+## Need Help?
+
+If you encounter any issues or have questions about the solution, refer to the main tutorial documentation or reach out to the Knative community for support.

code-samples/eventing/bookstore-sample-app/start/README.md

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+# Knative Bookstore Tutorial - Start Directory
+
+Welcome to the starting point of the Knative Bookstore tutorial. This directory contains the initial setup and base files for building your event-driven bookstore application using Knative.
+
+## Directory Structure
+
+Here's an overview of the components you'll be working with:
+
+- `db-service/`: Database service for storing book reviews and comments
+- `frontend/`: User interface for the bookstore application built with Next.js
+- `node-server/`: Node.js server for handling backend operations
+- `sequence/`: Knative Sequence setup for orchestrating workflows
+- `slack-sink/`: Integration with Slack for notifications with Apache Camel
+- `setup.sh`: Script for setting up the required services including installing Knative, frontend, and backend node-server
+## Getting Started
+
+1. Familiarize yourself with the directory structure above.
+2. Each subdirectory contains starter code and placeholders for the services you'll be building.
+3. Follow the [Knative Bookstore Tutorial](https://knative.dev/bookstore/page-0/welcome-knative-bookstore-tutorial/) for step-by-step instructions on how to implement each component.
+4. As you progress through the tutorial, you'll be adding code and configurations to these directories.
+
+Remember, this is just the starting point. By the end of the tutorial, you'll have a fully functional event-driven bookstore application.
+
+## Need Help?
+
+If you encounter any issues or have questions, refer to the main tutorial documentation or reach out to the Knative community for support.

docs/samples/README.md

@@ -9,6 +9,10 @@ Knative code samples that are actively tested and maintained by Knative working
 
 - [Eventing and Eventing Sources code samples](eventing.md)
 - [Serving code samples](serving.md)
+- [E2E Sample Application - Knative Bookstore](https://github.com/knative/docs/tree/main/code-samples/eventing/bookstore-sample-app)
+
+!!! tip
+    E2E Sample Application - Knative Bookstore is a sample application that demonstrates how to use all part of Knative: **Eventing, Serving, and Function**, to build a simple bookstore application.
 
 ## Community owned samples