Add article on Azure DevOps service connection security

[BlueBasher]

Pull Request Template

What are you trying to address

This PR adds an article that describes a potential security issue in Azure DevOps and how to fix that issue.

Description of new changes

A new article has been added that describes a security issue that can be present in an Azure DevOps setup regarding Service Connections. The article describes what the actual issue is and how Service Connections should be configured to fix the issue.

For all pull requests

• [ ] Link to the issue you are solving (so it gets closed)
• [ ] Label the pull request with the appropriate area(s)
• [ ] Assign potential reviewers (you may also want to contact them on Teams to ensure timely reviews)
• [ ] Assign the project - Engineering Playbook Backlog
• [ ] Assign the pull request to yourself

[TessFerrandez]

Thank you for the PR - generally I think the content is good, but I think perhaps it fits better in Continuous Delivery or Continuous Integration under dev-sec-ops -- there are some similar patterns in there. I think that might be where people would go to look for content of this nature... thoughts?

[BlueBasher]

Before creating the PR, I was in doubt whether it should be Security or Continuous Integration. But CI seems like a good fit indeed. I've moved the content and updated the PR.