This repo is missing a license file

[microsoft-github-policy-service[bot]]

This repository is currently missing a LICENSE.MD file outlining its license. A license helps users understand how to use your project in a compliant manner. You can find the standard MIT license text at the Microsoft repo templates LICENSE file: https://github.com/microsoft/repo-templates/blob/main/shared/LICENSE. If you would like to learn more about open source licenses, please visit the document at https://aka.ms/license.

[stliu]

Now the repo does have a license file but source codes do not have license header which I think it should be fixed as well