Example is not for a useful use case

Counting the number of TextChanged events is not a useful use case example. A more useful one would be to show how to filter out invalid characters or prevent the user from removing necessary text for example.

---
#### Document Details

⚠ *Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.*

* ID: 5200decc-0848-25a2-1308-d5e988354c58
* Version Independent ID: df52f522-ed38-9ee9-017b-a621a1d6789d
* Content: [TextChangedEventArgs Class (System.Windows.Controls)](https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.textchangedeventargs?view=netframework-4.7.2)
* Content Source: [xml/System.Windows.Controls/TextChangedEventArgs.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Windows.Controls/TextChangedEventArgs.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**