[Doc]: Get-AzWebApp doesn't allways give full details

### Type of issue

Other (describe below)

### Feedback

The App Service objects returned from `Get-AzWebApp -AppServicePlan 'myAppPlan'` does not contain all details (e.g. entity is always null).
Retrieving each individual App Service with `Get-AzWebApp -ResourceGroupName "Default-Web-WestUS" -Name "ContosoSite"` does give me all details.

Please make this clear in the documentation or enhance the first signature to provide full details (to make the signatures consistent).

### Page URL

https://learn.microsoft.com/en-us/powershell/module/az.websites/get-azwebapp

### Content source URL

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### Author

_No response_

### Document Id

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Start with the Get-AzWebApp documentation at the linked page and compare the -AppServicePlan and -ResourceGroupName/-Name invocation forms. Reproduce whether the App Service objects differ in detail, including the entity value. Done means either documenting the limitation clearly or making the signatures return consistent details, with the behavior verified.

Written by the indexing model from the issue text.