Adding Microsoft’s official mandatory file(s) to this repo

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

This repository needs the standard SECURITY.MD file to help the community understand the security policy and how to safely report security issues. GitHub uses the presence of this file to light-up security reminders and a link to the file. This pull request commits the latest SECURITY.MD file from https://github.com/microsoft/repo-templates/blob/main/shared/SECURITY.md.
If you have any questions inside Microsoft, you can refer to the resources at https://aka.ms/opensource.

[ghost]

All CLA requirements met.