Update 5.0 migration guide for RC1 release (#19853)

Author: scottaddie

aspnetcore/migration/31-to-50.md

@@ -4,7 +4,7 @@ author: scottaddie
 description: Learn how to migrate an ASP.NET Core 3.1 project to ASP.NET Core 5.0.
 ms.author: scaddie
 ms.custom: mvc
-ms.date: 08/26/2020
+ms.date: 09/14/2020
 no-loc: ["ASP.NET Core Identity", cookie, Cookie, Blazor, "Blazor Server", "Blazor WebAssembly", "Identity", "Let's Encrypt", Razor, SignalR]
 uid: migration/31-to-50
 ---
@@ -41,7 +41,7 @@ If you rely upon a [global.json](/dotnet/core/tools/global-json) file to target
 {
   "sdk": {
 -    "version": "3.1.200"
-+    "version": "5.0.100-preview.8.20417.9"
++    "version": "5.0.100-rc.1.20452.10"
   }
 }
 ```
@@ -65,6 +65,13 @@ If updating a Blazor WebAssembly project, skip to the [Update Blazor WebAssembly
 
 For Blazor WebAssembly projects, apply the following changes in the project file:
 
+1. Update the SDK from `Microsoft.NET.Sdk.Web` to `Microsoft.NET.Sdk.BlazorWebAssembly`:
+
+    ```diff
+    - <Project Sdk="Microsoft.NET.Sdk.Web">
+    + <Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">
+    ```
+
 1. Update the following properties:
 
     ```diff
@@ -74,8 +81,6 @@ For Blazor WebAssembly projects, apply the following changes in the project file
     -     <TargetFramework>netstandard2.1</TargetFramework>
     -     <RazorLangVersion>3.0</RazorLangVersion>
     +     <TargetFramework>net5.0</TargetFramework>
-    +     <RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
-    +     <UseBlazorWebAssembly>true</UseBlazorWebAssembly>
       </PropertyGroup>
     ```
 
@@ -95,9 +100,9 @@ In the project file, update each [Microsoft.AspNetCore.*](https://www.nuget.org/
 -    <PackageReference Include="Microsoft.AspNetCore.JsonPatch" Version="3.1.6" />
 -    <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="3.1.6" />
 -    <PackageReference Include="System.Net.Http.Json" Version="3.2.1" />
-+    <PackageReference Include="Microsoft.AspNetCore.JsonPatch" Version="5.0.0-preview.8.*" />
-+    <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="5.0.0-preview.8.*" />
-+    <PackageReference Include="System.Net.Http.Json" Version="5.0.0-preview.8.*" />
++    <PackageReference Include="Microsoft.AspNetCore.JsonPatch" Version="5.0.0-rc.1.*" />
++    <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="5.0.0-rc.1.*" />
++    <PackageReference Include="System.Net.Http.Json" Version="5.0.0-rc.1.*" />
 </ItemGroup>
 ```