Move publish step to GitHub Action & use env var instead of --token

[mdanish-kh]

Change

Move azure pipeline step to a GitHub Action. Using an environment variable instead of --token param as per the latest recommendation. To add a personal access token (PAT), one can follow the steps listed in https://github.com/microsoft/winget-create?tab=readme-ov-file#github-personal-access-token-classic-permissions. We'll need to create a repository secret with a name WINGET_CREATE_GITHUB_TOKEN (can choose smth else too)

Updated the README with the latest changes and resolved formatting markdownlint errors as well

Microsoft Reviewers: Open in CodeFlow