Update deployment guides

[jonathanscholtes]

This pull request updates documentation and configuration files to improve clarity, accuracy, and usability for deploying and operating the Azure SRE Agent demo. The changes focus on clarifying terminology, updating deployment instructions, adding troubleshooting guidance, and ensuring region requirements are consistent across files.

Documentation improvements and clarification:

• Added links to a companion architecture article in both README.md and docs/walkthrough.md for additional context. [1] [2]
• Updated terminology throughout the documentation for consistency (e.g., "ADO WorkItem" → "Azure DevOps work item", "files an ADO WorkItem" → "files an Azure DevOps work item"). [1] [2] [3]

Deployment and configuration guidance:

• Expanded and clarified deployment steps in docs/deployment.md, including new sections for configuring incident platforms, connectors, and response plans in the Azure portal. Steps for adding Azure DevOps and GitHub as automated destinations are now more detailed and accurate.
• Added a troubleshooting section to docs/deployment.md to help users resolve common setup issues.
• Updated instructions and descriptions for Terraform variables and deployment commands for clarity and accuracy, including default values and region constraints. [1] [2] [3] [4]

Usability and workflow enhancements:

• Improved walkthrough instructions in docs/walkthrough.md, including a more detailed verification checklist and clearer reset instructions. [1] [2]
• Updated references to branch protection and status checks in README.md and deployment docs to match actual workflow file names and clarify enforcement. [1] [2] [3]

Legal and copyright:

• Updated the copyright year range in LICENSE.md.

Region support consistency:

• Removed uksouth from the list of supported regions for SRE Agent deployment in all relevant files for consistency. [1] [2] [3]

These changes make the deployment process smoother, reduce ambiguity, and help users troubleshoot and understand the self-healing pipeline more effectively.