Add .NET Feature Management 4.6.0 release notes (#1160)

* Add Microsoft.FeatureManagement 4.6.0 release notes

* Simplify 4.6.0 keyed DI release note wording

* Remove 4.6.0 release note code snippet

* Add 4.6.0 related FeatureManagement release notes

* Update 4.6.0 release date to July 1, 2026

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

releaseNotes/Microsoft.Featuremanagement.AspNetCore.md

@@ -2,6 +2,10 @@
 
 [Source code][source_code] | [Package (NuGet)][package] | [Samples][samples] | [Product documentation][docs]
 
+## 4.6.0 - July 1, 2026
+
+* Updated `Microsoft.FeatureManagement` reference to `4.6.0`. See the [release notes](./Microsoft.Featuremanagement.md) for more information on the changes.
+
 ## 4.5.0 - April 23, 2026
 
 * Updated `Microsoft.FeatureManagement` reference to `4.5.0`. See the [release notes](./Microsoft.Featuremanagement.md) for more information on the changes.

releaseNotes/Microsoft.Featuremanagement.Telemetry.ApplicationInsights.md

@@ -2,6 +2,10 @@
 
 [Source code][source_code] | [Package (NuGet)][package] | [Samples][samples] | [Product documentation][docs]
 
+## 4.6.0 - July 1, 2026
+
+* Updated `Microsoft.FeatureManagement` reference to `4.6.0`. See the [release notes](./Microsoft.Featuremanagement.md) for more information on the changes.
+
 ## 4.5.0 - April 23, 2026
 
 * Updated `Microsoft.FeatureManagement` reference to `4.5.0`. See the [release notes](./Microsoft.Featuremanagement.md) for more information on the changes.

releaseNotes/Microsoft.Featuremanagement.md

@@ -2,6 +2,12 @@
 
 [Source code][source_code] | [Package (NuGet)][package] | [Samples][samples] | [Product documentation][docs]
 
+## 4.6.0 - July 1, 2026
+
+### Enhancements
+
+* Added support for resolving variant service implementations through keyed dependency injection. This enables lazy, on-demand instantiation for scenarios where each implementation has its own dependencies and configuration. [#564](https://github.com/microsoft/FeatureManagement-Dotnet/issues/564)
+
 ## 4.5.0 - April 23, 2026
 
 ### Enhancements