Add Telemetry Documentation (#345)

- Created a new page that describes what telemetry is collected, how
it’s used, and how to opt out.
- Updated README for the repo and the Docs homepage to reflect that
telemetry collection is now in place.
---

### **Checklist**
- [ ] Tests added/updated
- [x] Documentation updated (if needed)
- [ ] Code conforms to style guidelines

Author: kavyamsft

README.md

@@ -32,6 +32,14 @@ detailed instructions on getting started and building.
 Have questions, found a bug, or need a new feature? Open an issue in our [GitHub
 repository](https://github.com/microsoft/azure-linux-image-tools/issues/new?template=Blank+issue).
 
+## Telemetry
+
+Image Customizer collects usage data to help improve the product. This data
+helps us understand usage patterns, diagnose issues, improve reliability, and
+prioritize new features based on real-world usage. Learn how Image Customizer
+collects and uses telemetry, and how to opt out
+[here](https://microsoft.github.io/azure-linux-image-tools/imagecustomizer/telemetry.html).
+
 ---
 
 ## Trademarks

docs/imagecustomizer/README.md

@@ -61,6 +61,13 @@ other Linux distributions as well.
   - [Configuration](./api/configuration.md) - Understand how to configure Image
     Customizer to suit your needs
 
+## Telemetry 
+
+Image Customizer collects usage data to help improve the product. This data
+helps us understand usage patterns, diagnose issues, improve reliability, and
+prioritize new features based on real-world usage. Learn how Image Customizer
+collects and uses telemetry, and how to opt out [here](telemetry.md).
+
 ## Help and Feedback
 
 If you'd like to report bugs, request features, or contribute to the tool, you

docs/imagecustomizer/telemetry.md

@@ -0,0 +1,62 @@
+---
+title: Telemetry
+parent: Image Customizer
+nav_order: 7
+---
+
+# Telemetry in Image Customizer
+
+Image Customizer collects usage data to help improve the product. This data
+helps us understand usage patterns, diagnose issues, improve reliability and
+prioritize new features based on real-world usage. This section describes what
+telemetry is collected, how it’s used, and how to opt out. 
+
+## Scope 
+
+Image Customizer can be run in two ways:
+
+- As a container image downloaded from Microsoft Artifact Registry
+- As a binary built from the GitHub repository
+
+Telemetry is collected in both cases. 
+
+## How to opt out 
+
+Telemetry collection for Image Customizer is enabled by default. To opt out, use
+the flag `--disable-telemetry`. Here is a sample command: 
+
+```bash
+docker run \
+   --rm \
+   --privileged=true \
+   -v /dev:/dev \
+   -v "$HOME/staging:/mnt/staging:z" \
+   mcr.microsoft.com/azurelinux/imagecustomizer:0.15.0 \
+   imagecustomizer \
+     --image-file "/mnt/staging/image.vhdx" \
+     --config-file "/mnt/staging/image-config.yaml" \
+     --build-dir "/build" \
+     --output-image-format "vhdx" \
+     --output-image-file "/mnt/staging/out/image.vhdx"
+     --disable-telemetry
+```
+
+### Data Collection and Storage 
+
+Image Customizer doesn't collect personal data, such as IP addresses, usernames,
+Azure subscription IDs or email addresses. Telemetry is collected using the
+[OpenTelemetry (OTel)](https://learn.microsoft.com/en-us/azure/azure-monitor/app/opentelemetry-overview)
+framework and is stored securely in an Azure Monitor Workspace to be used only
+for product improvement and diagnostics. 
+
+The telemetry feature collects the following data: 
+
+| Category          |Examples                                                                  |
+|-------------------|--------------------------------------------------------------------------|
+| Usage Metrics     | Number of image customizations, API call frequency, Number of Image Customizer downloads |
+| Environment Info  | Host OS (e.g., WSL, Ubuntu, Azure Linux), base image-format              |
+| Performance       | Image creation success and failure rates, error codes, Time taken to create images |
+
+
+Protecting your privacy is important to us. You can always opt out and continue
+using the tool without restrictions.