Yunho/readonly flag test

[yunho-microsoft]

How contribute to this repo.

Guidelines for Pull Requests.

The sections included below are suggestions for what you may want to include.
Feel free to remove or alter parts of this template that do not offer value for your specific change.

Description

A concise description of the changes (bug or feature) and their impact/motivation.
If this description is short enough to be used as the title, delete this section and just use the title.

For bug fixes, also include specifics of how to reproduce it / confirm it is fixed.

If this Pull Request should close/resolve any issues when merged, use the special syntax for that here.

Breaking Changes

If this introduces a breaking change, please describe the impact and migration path for existing applications below.
See Breaking-vs-Non-breaking-Changes for details.
If there are no breaking changes, delete this section.

Reviewer Guidance

The review process is outlined on this wiki page.

List any specific things you want to get reviewer opinions on, and anything a reviewer would need to know to review this PR effectively.
Things you might want to include:

• Questions about how to properly make automated tests for your changes.
• Questions about design choices you made.
• Descriptions of how to manually test the changes (and how much of that you have done).
• etc.

If you have any questions in this section, consider making the PR a draft until all questions have been resolved.

[github-actions]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> fluid-framework-docs-site@0.0.0 ci:check-links /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test "npm run serve -- --no-open" 3000 check-links

1: starting server using command "npm run serve -- --no-open"
and when url "[ 'http://127.0.0.1:3000' ]" is responding with HTTP status code 200
running tests using command "npm run check-links"


> fluid-framework-docs-site@0.0.0 serve
> docusaurus serve --no-open

[SUCCESS] Serving "build" directory at: http://localhost:3000/

> fluid-framework-docs-site@0.0.0 check-links
> linkcheck http://localhost:3000 --skip-file skipped-urls.txt

Crawling...

Stats:
  195689 links
    1565 destination URLs
    1797 URLs ignored
       0 warnings
       0 errors