ASPNET Core SignalR Supported platforms (#6021)

* ASPNET Core SignalR Supported platforms

* changes

aspnetcore/signalr/supported-platforms.md

@@ -0,0 +1,38 @@
+---
+title: ASP.NET Core SignalR supported platforms
+author: rachelappel
+description: Supported platforms for ASP.NET Core SignalR 
+manager: wpickett
+monikerRange: '>= aspnetcore-2.1'
+ms.author: rachelap
+ms.custom: mvc
+ms.date: 04/20/2018
+ms.prod: aspnet-core
+ms.technology: aspnet
+ms.topic: article
+uid: signalr/supported-platforms
+---
+
+# ASP.NET Core SignalR supported platforms
+
+## Server system requirements
+
+SignalR for ASP.NET Core supports any server platform ASP.NET Core supports.
+
+## Client system requirements
+
+### Browser support
+
+The SignalR for ASP.NET Core JavaScript client supports the following browsers:
+
+| Browser | Version |
+| ------- | ------- |
+| Microsoft Internet Explorer | 11 |
+| Microsoft Edge | current |
+| Mozilla Firefox | current |
+| Google Chrome; includes Android | current |
+| Safari; includes iOS | current |
+ 
+### .NET Client support
+
+Any server platform supported by ASP.NET Core. When using IIS, the WebSockets transport requires IIS 8.0 or higher, on Windows Server 2012 or higher. Other transports are supported on all platforms.

aspnetcore/toc.md

@@ -226,6 +226,7 @@
 ## [Get started](xref:signalr/get-started)
 ## [Hubs](xref:signalr/hubs)
 ## [JavaScript client](xref:signalr/javascript-client)
+## [Supported Platforms](xref:signalr/supported-platforms)
 
 # [Mobile](xref:mobile/index)
 ## [Create backend services for native mobile apps](xref:mobile/native-mobile-backend)