updating signalr js package readme (#22129)

* updating signalr js package readme

* Update src/SignalR/clients/ts/signalr/README.md

Co-authored-by: Brennan <brecon@microsoft.com>

* Update PatchConfig.props

Co-authored-by: Brennan <brecon@microsoft.com>

eng/PatchConfig.props

@@ -63,6 +63,7 @@ Later on, this will be checked using this condition:
   </PropertyGroup>
   <PropertyGroup Condition=" '$(VersionPrefix)' == '2.1.20' ">
     <PackagesInPatch>
+      @aspnet/signalr;
     </PackagesInPatch>
   </PropertyGroup>
 </Project>

src/SignalR/clients/ts/signalr/README.md

 JavaScript and TypeScript clients for SignalR for ASP.NET Core
 
+> Note: The JavaScript and TypeScript clients for SignalR for ASP.NET Core have been moved to [@microsoft/signalr](https://www.npmjs.com/package/@microsoft/signalr). If you are already using `@aspnet/signalr` and are unsure when to move to `@microsoft/signalr`, check the [Feature Distribution](https://docs.microsoft.com/en-us/aspnet/core/signalr/client-features) chart in the ASP.NET Core SignalR documentation. Newer client releases are compatible with older version of ASP.NET Core SignalR which means it is safe to upgrade the client before upgrading the server.
+
 ## Installation
 
 ```bash