Add new property and update "is bindable property"

[jfversluis]

Fixes NA

Docs for Toolkit PR #836

What changes to the docs does this PR provide?

Adds new property to the docs and noting which properties are bindable properties

PR Checklist

Please check if your PR fulfills the following requirements:

• 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

[davidbritch]

Docs Build status updates of commit aad12d3:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/behaviors/validationbehavior.md	✅Succeeded	View

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[davidbritch]

Thanks @jfversluis