ES5 support in SIgnalR /6 (dotnet#28325)

* ES5 support in SIgnalR /6

* ES5 support in SIgnalR /6

Author: Rick-Anderson

aspnetcore/includes/SignalR/es6.md

@@ -0,0 +1,5 @@
+<a name="es6"></a>
+
+## Browsers that don't support ECMAScript 6 (ES6)
+
+SignalR targets ES6. For browsers that don't support ES6, transpile the library to ES5. For more information, see [Getting Started with ES6 – Transpiling ES6 to ES5 with Traceur and Babel](https://weblogs.asp.net/dwahlin/getting-started-with-es6-%E2%80%93-transpiling-es6-to-es5).

aspnetcore/signalr/client-features.md

@@ -44,6 +44,8 @@ The table below shows the features and support for the clients that offer real-t
 
 Support for enabling additional client features is tracked in [our issue tracker](https://github.com/dotnet/AspNetCore/issues).
 
+[!INCLUDE[](~/includes/SignalR/es6.md)]
+
 ## Additional resources
 
 * [Get started with SignalR for ASP.NET Core](xref:tutorials/signalr)

aspnetcore/signalr/introduction.md

@@ -51,10 +51,13 @@ A hub is a high-level pipeline that allows a client and server to call methods o
 
 Hubs call client-side code by sending messages that contain the name and parameters of the client-side method. Objects sent as method parameters are deserialized using the configured protocol. The client tries to match the name to a method in the client-side code. When the client finds a match, it calls the method and passes to it the deserialized parameter data.
 
+[!INCLUDE[](~/includes/SignalR/es6.md)]
+
 ## Additional resources
 
 * [Introduction to ASP.NET Core SignalR](/training/modules/aspnet-core-signalr)
 * [Get started with SignalR for ASP.NET Core](xref:tutorials/signalr)
 * [Supported Platforms](xref:signalr/supported-platforms)
 * [Hubs](xref:signalr/hubs)
 * [JavaScript client](xref:signalr/javascript-client)
+* [Browsers that don't support ECMAScript 6 (ES6)](xref:signalr/supported-platforms#es6)

aspnetcore/signalr/supported-platforms.md

@@ -45,3 +45,5 @@ The following clients are available but are experimental or unofficial. The foll
 
 * [C++ client](https://github.com/aspnet/SignalR-Client-Cpp)
 * [Swift client](https://github.com/moozzyk/SignalR-Client-Swift)
+
+[!INCLUDE[](~/includes/SignalR/es6.md)]