Setup for edits to Progress Controls doc

[YuliKl]

We're updating the appearance of ProgressBar, adding a re-written version of the control to WinUI. microsoft/microsoft-ui-xaml#1169

Sending out a preliminary PR to work out the right process of staging changes that should go live when WinUI 2.3 releases in a couple weeks. Which branch should I be checking changes into to ensure these additions go smoothly?

[PRMerger18]

@YuliKl : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[Jak-MS]

@YuliKl - can you resubmit the commits in this pull request to the private repo https://github.com/MicrosoftDocs/windows-uwp-pr ? That way we can take advantage of proofing, staging, and validation tools to ensure the quality criteria are met. Thanks.

Microsoft authors and contributors need to make content contributions through the private repository so the content can be staged and validated by the current validation rules.

After you review staging and fix all validation issues, you can tag an author for review or add the sign-off comment to let PR reviewers know that the updates are ready to be merged.

Read about authors working in the public repo for more information.

If you need help getting set up to work in the private repo, see How to get to the private repo. You can also take a look at the GitHub account setup page for additional details on making sure you're set up.

We'll close this PR. Thank you.