Dotnet provider 8.6.0-preview release notes (#1136)

* Dotnet provider 8.6.0-preview release notes

* update

Author: linglingye001

releaseNotes/MicrosoftAzureAppConfigurationAspNetCore.md

@@ -1,6 +1,9 @@
 # Microsoft.Azure.AppConfiguration.AspNetCore
 [Source code][source_code] | [Package (NuGet)][package]
 
+## 8.6.0-preview - February 26th, 2026
+* Updated `Microsoft.Extensions.Configuration.AzureAppConfiguration` reference to `8.6.0-preview`. See the [release notes](./MicrosoftExtensionsConfigurationAzureAppConfiguration.md) for more information on the changes.
+
 ## 8.5.0 - February 12th, 2026
 * Updated `Microsoft.Extensions.Configuration.AzureAppConfiguration` reference to `8.5.0`. See the [release notes](./MicrosoftExtensionsConfigurationAzureAppConfiguration.md) for more information on the changes.
 

releaseNotes/MicrosoftAzureAppConfigurationFunctionsWorker.md

@@ -1,6 +1,9 @@
 # Microsoft.Azure.AppConfiguration.Functions.Worker
 [Source code][source_code] | [Package (NuGet)][package]
 
+## 8.6.0-preview - February 26th, 2026
+* Updated `Microsoft.Extensions.Configuration.AzureAppConfiguration` reference to `8.6.0-preview`. See the [release notes](./MicrosoftExtensionsConfigurationAzureAppConfiguration.md) for more information on the changes.
+
 ## 8.5.0 - February 12th, 2026
 * Updated `Microsoft.Extensions.Configuration.AzureAppConfiguration` reference to `8.5.0`. See the [release notes](./MicrosoftExtensionsConfigurationAzureAppConfiguration.md) for more information on the changes.
 

releaseNotes/MicrosoftExtensionsConfigurationAzureAppConfiguration.md

@@ -1,10 +1,17 @@
 # Microsoft.Extensions.Configuration.AzureAppConfiguration
 [Source code][source_code] | [Package (NuGet)][package]
 
+## 8.6.0-preview - February 26th, 2026
+### Enhancements
+* Optimized refresh behavior for `ConnectAzureFrontDoor` by using `HEAD` requests to check for changes. [#717](https://github.com/Azure/AppConfiguration-DotnetProvider/pull/717)
+
 ## 8.5.0 - February 12th, 2026
 ### Enhancements
 * Upgraded the package reference for `Azure.Data.AppConfiguration` to `1.8.0`to take advantage of enhanced errors when Entra ID audience is misconfigured. [#721](https://github.com/Azure/AppConfiguration-DotnetProvider/pull/721)
 
+### Bug Fixes
+* Fixed a bug where the Azure App Configuration health check did not honor the registered `failureStatus` when the provider failed to load or refresh. [#714](https://github.com/Azure/AppConfiguration-DotnetProvider/pull/714)
+
 ## 8.5.0-preview - November 14th, 2025
 ### Enhancements
 * Added a new method `ConnectAzureFrontDoor` to `AzureAppConfigurationOptions`, which can be used to load configuration settings from Azure App Configuration via an Azure Front Door endpoint. This enables client-side applications (like mobile/desktop apps) to securely load configuration from App Configuration service, while leveraging all the benefits of CDN. [#706](https://github.com/Azure/AppConfiguration-DotnetProvider/pull/706)