Add document with instructions on how to test prerelease workload sets (#490)

* Add document with instructions on how to test prerelease workload sets

* Update based on PR review feedback

* Update based on current state of pipeline

* Fix example branch name format in documentation

Updated the example branch name format in the documentation.

Author: marcpopMSFT

doc/test-workload-updates.md

@@ -0,0 +1,91 @@
+# Test Workload Updates Process
+
+This document provides instructions for the MAUI, Android, and iOS teams on how to create test workload sets for validation and testing purposes.
+
+## Overview
+
+Test workload sets allow teams to validate workload updates before they are included in official releases. This process supports two main scenarios:
+1. Creating test workload sets for general validation
+2. Creating test workload sets with Visual Studio insertion for integration testing
+
+## Prerequisites
+
+- Access to the workload-versions repository
+- Permissions to create branches and pull requests
+- Access to Azure DevOps internal builds
+
+## Process Steps
+
+### 1. Create a Test Branch
+
+1. **Branch from a release branch**: Start by creating a test branch from one of the existing release branches
+   ```
+   Example branch name: release/9.0.3xx-mauitest
+   ```
+   
+   **Branch naming convention:**
+   - `release/{version}/mauitest{mauiversion}` - for MAUI team tests
+   - `release/{version}/androidtest{androidversion}` - for Android team tests  
+   - `release/{version}/iostest{iosversion}` - for iOS team tests
+
+2. **Make your changes**: Update the necessary workload configurations in your test branch
+
+### 2. Create and Merge Pull Request
+
+1. **Publish your test build to a Darc channel**: After making changes, publish the build artifacts to a dedicated Darc channel for test workloads.
+2. **Use `darc update-dependencies`**: Run `darc update-dependencies` to update your test branch with the new build information from the Darc channel. This ensures your branch references the correct test workload versions.
+3. **Get approval** from the appropriate reviewers
+4. **Merge the PR** once approved
+
+> **Note**: Once the test pipeline is established, PRs will not be required and teams can push directly to the internal Azure DevOps repository.
+
+### 3. Queue Internal Build
+
+After merging your PR, queue an internal build using the Azure DevOps pipeline.
+https://dev.azure.com/dnceng/internal/_build?definitionId=1298
+
+## Build Configuration Options
+
+When queuing the pipeline, you have several configuration options depending on your testing needs:
+
+### For Test Workload Sets Only
+
+If you only need to create a test workload set:
+
+1. ✅ **Select pipeline version by branch/tag** set to **eng**
+2. ✅ **🚩 Source branch 🚩** set to your branch
+3. ✅ **Select "Publish to AzDO"** when queuing the pipeline
+4. ✅ **AzDO publish feed** is the feed it'll publish the workload set to. Default should be _dotnet-workloads_.
+5. ✅ **⭐ Create a test workload set** enabled
+   - This will generate the test workload set for validation that is of the form
+   - The workload set will be published to Azure DevOps for testing
+
+### For Visual Studio Insertion Testing
+
+If you need to test a Visual Studio insertion:
+
+1. ✅ **Update the workload drop names** for the workloads you want to update in VS
+2. ✅ **Update the primary VS insertion branch** configuration
+3. ✅ **Check the box for "Create VS insertion"**
+
+This configuration will:
+- Create the test workload set
+- Prepare the workloads for VS insertion
+- Initiate the insertion process into the specified VS branch
+
+## Important Notes
+
+- **Branch Management**: Keep test branches organized and clean up after testing is complete
+- **Communication**: Coordinate with other teams if multiple test branches are being used simultaneously
+
+## Troubleshooting
+
+If you encounter issues during the process:
+
+1. **Build Failures**: Check the build logs in Azure DevOps for specific error messages
+2. **Permission Issues**: Ensure you have the necessary access rights for the repositories and pipelines
+4. **Workload Set Versioning**: The workload set created will match the SDK band specified in the `Versions.props` file.
+
+## Support
+
+For additional support or questions about this process, please reach out to the .NET SDK team on our Teams chat.