CollectionView does not display grouped data header by default

### Type of issue

Code doesn't work

### Description

When passing in a collection of group items with name attributes as the CollectionView ItemsSource, the names are not displayed as the header by default like it says in the documentation. A GroupHeaderTemplate must be made and the Name attribute must be passed into it for the header to be displayed.

With GroupHeaderTemplate

Without GroupHeaderTemplate

### Page URL

https://learn.microsoft.com/en-us/dotnet/maui/user-interface/controls/collectionview/grouping?view=net-maui-8.0

### Content source URL

https://github.com/dotnet/docs-maui/blob/main/docs/user-interface/controls/collectionview/grouping.md

### Document Version Independent Id

56201296-c616-f9e0-bf20-e44931abe815

### Article author

@davidbritch

### Metadata

* ID: 56201296-c616-f9e0-bf20-e44931abe815
* Service: **dotnet-mobile**
* Sub-service: **dotnet-maui**