Improve Color page sample code

[AndrewKeepCoding]

Description

Added sample code for the theme resource brush use.

Motivation and Context

How Has This Been Tested?

Ran the app and confirme the change.

Screenshots (if appropriate):

Before:

After:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[niels9001]

Could we do just the XAML string as a code block and not the Expander? The core functionality of this tool is to quickly look up brushes, having the expander here would introduce additional scrolling and pushes down the most important info.. thoughts?

[AndrewKeepCoding]

Something like this?

[niels9001]

Nit: can we shorten the 'Text="..."' and keep everything on a single line?

[AndrewKeepCoding]

Nit: can we shorten the 'Text="..."' and keep everything on a single line?

Pushed the changes.