[AppConfig] Some doc issues

[YalinLi0312]

Here are some issues found in AppConfig doc:

• Missing content
  https://learn.microsoft.com/en-us/python/api/azure-appconfiguration/azure.appconfiguration.aio.azureappconfigurationclient?view=azure-python#parameters
  

• Code snippet format errors
  https://learn.microsoft.com/en-us/python/api/azure-appconfiguration/azure.appconfiguration.azureappconfigurationclient?view=azure-python#azure-appconfiguration-azureappconfigurationclient-list-revisions
  

• Incorrectly parsed HTML elements
  https://learn.microsoft.com/en-us/python/api/azure-appconfiguration/azure.appconfiguration.aio.azureappconfigurationclient?view=azure-python#azure-appconfiguration-aio-azureappconfigurationclient-list-labels
  

• Unnecessary symbols
  https://learn.microsoft.com/en-us/python/api/azure-appconfiguration/azure.appconfiguration.configurationsetting?view=azure-python#azure-appconfiguration-configurationsetting-as-dict
  

• Incorrect hyperlinks
  https://learn.microsoft.com/en-us/python/api/overview/azure/appconfiguration-readme?view=azure-python
  

Has been fixed in #37281

• Missing type annotations
  https://learn.microsoft.com/en-us/python/api/azure-appconfiguration-provider/azure.appconfiguration.provider.aio.azureappconfigurationprovider?view=azure-python#constructor
  
  @mrm9084 Can you help to fix this issue in provider?