(AzureCXP) Fixes MicrosoftDocs/azure-docs#50014

Added instructions for installation of Microsoft.FeatureManagement NuGet package

Author: BhargaviAnnadevara

articles/azure-app-configuration/use-feature-flags-dotnet-core.md

@@ -35,6 +35,18 @@ In this tutorial, you will learn how to:
 
 ## Set up feature management
 
+Add reference to the `Microsoft.FeatureManagement` NuGet package by running the following command from Visual Studio Package Manager Console:
+
+```dotnetcli
+dotnet add package Microsoft.FeatureManagement
+```
+
+Run the following command to restore packages for your project:
+
+```dotnetcli
+dotnet restore
+```
+    
 The .NET Core feature manager `IFeatureManager` gets feature flags from the framework's native configuration system. As a result, you can define your application's feature flags by using any configuration source that .NET Core supports, including the local *appsettings.json* file or environment variables. `IFeatureManager` relies on .NET Core dependency injection. You can register the feature management services by using standard conventions:
 
 ```csharp