Added intro blog post (#1)

Author: csharpfritz

README.md

@@ -161,6 +161,7 @@ public class CustomConfigBuilder : KeyValueConfigBuilder
 ```
 
 ## Blog Posts
+[Announcing .NET 4.7.1 Tools for the Cloud](https://blogs.msdn.microsoft.com/webdev/2017/11/17/announcing-net-4-7-1-tools-for-the-cloud/)
 [.Net Framework 4.7.1 ASP.NET and Configuration features](https://blogs.msdn.microsoft.com/dotnet/2017/09/13/net-framework-4-7-1-asp-net-and-configuration-features/)
 [Modern Configuration for ASP.NET 4.7.1 with ConfigurationBuilders](http://jeffreyfritz.com/2017/11/modern-configuration-for-asp-net-4-7-1-with-configurationbuilders/)  
 [Service-to-service authentication to Azure Key Vault using .NET](https://docs.microsoft.com/en-us/azure/key-vault/service-to-service-authentication#connection-string-support)