Misleading and broken code example for "Manually reconnect" after SignalR connection closed

### Description

The section "Manually reconnect" contains this example:

```csharp
connection.Closed += async (error) =>
{
await Task.Delay(new Random().Next(0,5) * 1000);
await connection.StartAsync();
};
```

However, I could not get this to work and I've spent an annoying amount of time double-checking I had followed the various steps in the setup.

As far as I can tell, this example code is broken and not reliable, because if the network or server is not back and accepting connections within a second or 2, *the call to `StartAsync()` will throw an exception, the connection attempt will be abandoned, and there will be no new call to the `Closed` handler, so no additional attempts will be made*:

```
System.Net.Http.HttpRequestException: Connection refused (localhost:7321)
---> System.Net.Sockets.SocketException (111): Connection refused
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
at System.Net.Sockets.Socket.g__WaitForConnectWithCancellation|277_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
```

The code example does not show this and the surrounding text doesn't even hint about it. Quite the opposite, the current text in that section gives a clear impression that it is all you need to do.

I think the section should at least point this out.

For what it's worth, it seems calling the `ConnectWithRetryAsync()` method, provided earlier in the article, from the `Closed` event handler instead of directly calling `StartAsync()` makes it more robust.

### Page URL

https://learn.microsoft.com/en-us/aspnet/core/signalr/dotnet-client?view=aspnetcore-8.0&tabs=visual-studio

### Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/signalr/dotnet-client.md

### Document ID

36052173-7061-6d01-8aed-915685cd7cf6

### Article author

@bradygaster