Update the workflow to target the main branch

[janechu]

Pull Request

📖 Description

Due to the updates needed for beachball to ensure a good workflow process for publishing, the release branch is renamed to main and pull requests must now be merged to main.

Refer to https://github.com/microsoft/fast-tooling/issues/78 for more details.

👩‍💻 Reviewer Notes

Consider if there are any other locations where the release branch is referenced which should be changed to main.

✅ Checklist

General

• [ ] I have added tests for my changes.
• [ ] I have tested my changes.
• [x] I have updated the project documentation to reflect my changes.

⏭ Next Steps