Update DataGrid page with correct links

[alvinashcraft]

Remove links to see the control in action.

Add links to WinUI 2 Control Gallery app and Windows Community Toolkit Gallery app.

Add note about the DataGrid not being available in the latest Windows Community Toolkit.

Fixes #

Docs for Toolkit PR #

What changes to the docs does this PR provide?

PR Checklist

Please check if your PR fulfills the following requirements:

• Correctly picked the right branch to base the change off (dev for new features, main for typos/improvements)
• For new pages, used the provided template
• For new features, added an entry in the Table of Contents
• Ran against a spell and grammar checker
• Contains NO breaking changes

Other information

[learn-build-service-prod]

Learn Build status updates of commit 0a85ada:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/controls/DataGrid.md	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 2b7cf99:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/controls/DataGrid.md	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[alvinashcraft]

@michael-hawker Can you take a look at this PR when you have time? I don't have permissions on this repo to assign or merge anything. Thanks!

[michael-hawker]

Thanks @alvinashcraft, good to get this updated for now, and we're going to be working to add the redirects for all these docs to the new docs repo (https://github.com/MicrosoftDocs/CommunityToolkit) and then archive this one.