Add Blazor supported platforms topic (#12488)

aspnetcore/blazor/supported-platforms.md

@@ -0,0 +1,43 @@
+---
+title: ASP.NET Core Blazor supported platforms
+author: guardrex
+description: Learn about the supported platforms for ASP.NET Core Blazor.
+monikerRange: '>= aspnetcore-3.0'
+ms.author: riande
+ms.custom: mvc
+ms.date: 05/21/2019
+uid: blazor/supported-platforms
+---
+# ASP.NET Core Blazor supported platforms
+
+By [Luke Latham](https://github.com/guardrex)
+
+## Browser requirements
+
+### Blazor client-side
+
+| Browser                          | Version               |
+| -------------------------------- | :-------------------: |
+| Microsoft Edge                   | Current               |
+| Mozilla Firefox                  | Current               |
+| Google Chrome, including Android | Current               |
+| Safari, including iOS            | Current               |
+| Microsoft Internet Explorer      | Not Supported† |
+
+†Microsoft Internet Explorer doesn't support [WebAssembly](http://webassembly.org).
+
+For more information on the Blazor client-side hosting model, see <xref:blazor/hosting-models#client-side>.
+
+### Blazor server-side
+
+| Browser                          | Version    |
+| -------------------------------- | :--------: |
+| Microsoft Edge                   | Current    |
+| Mozilla Firefox                  | Current    |
+| Google Chrome, including Android | Current    |
+| Safari, including iOS            | Current    |
+| Microsoft Internet Explorer      | 11&dagger; |
+
+&dagger;Additional polyfills are required (for example, promises can be added via a [Polyfill.io](https://polyfill.io/v3/) bundle).
+
+For more information on the Blazor server-side hosting model, see <xref:blazor/hosting-models#server-side>.

aspnetcore/toc.yml

@@ -277,6 +277,8 @@
       items:
         - name: Overview
           uid: blazor/index
+        - name: Supported platforms
+          uid: blazor/supported-platforms
         - name: Get started
           uid: blazor/get-started
         - name: Hosting models