Fix invalid XML comment in SettingsExpander

[michael-hawker]

Fixes

PR Type

What kind of change does this PR introduce?

What is the current behavior?

What is the new behavior?

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• Tested code with current supported SDKs
• New component
  • Documentation has been added
  • Sample in sample app has been added
  • Analyzers are passing for documentation and samples
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (if applicable)
• Header has been added to all new source files
• Contains NO breaking changes

Other information

[michael-hawker]

Some other warnings I saw:

7>I:\code\WindowsToolkit-main\components\Animations\src\Expressions\ExpressionNodes\QuaternionNode.cs(14,19,14,19): warning CS1570: XML comment has badly formed XML -- 'A string literal was expected, but no opening quotation mark was found.'
7>I:\code\WindowsToolkit-main\components\Animations\src\Xaml\Abstract\CustomAnimation{TValue,TKeyFrame}.cs(29,1,29,1): warning CS1570: XML comment has badly formed XML -- 'Expected an end tag for element 'summary'.'
7>I:\code\WindowsToolkit-main\components\Animations\src\Xaml\Abstract\CustomAnimation{TValue,TKeyFrame}.cs(31,9,31,10): warning CS1570: XML comment has badly formed XML -- 'End tag was not expected at this location.'