Clarify KeepAliveInterval description in configuration (#36867)

* Clarify KeepAliveInterval description in configuration

dotnet/aspnetcore#65336 (comment)

* Update aspnetcore/signalr/configuration.md

---------

Co-authored-by: Wade Pickett <wpickett@microsoft.com>

Author: BrennanConroy

aspnetcore/signalr/configuration.md

@@ -68,7 +68,7 @@ The following table describes options for configuring SignalR hubs:
 | ------ | ------------- | ----------- |
 | `ClientTimeoutInterval` | 30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the `KeepAliveInterval` value.|
 | `HandshakeTimeout` | 15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the [SignalR Hub Protocol Specification](https://github.com/aspnet/SignalR/blob/master/specs/HubProtocol.md). |
-| `KeepAliveInterval` | 15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing `KeepAliveInterval`, change the `ServerTimeout` or `serverTimeoutInMilliseconds` setting on the client. The recommended `ServerTimeout` or `serverTimeoutInMilliseconds` value is double the `KeepAliveInterval` value.  |
+| `KeepAliveInterval` | 15 seconds | The interval at which a ping message is sent automatically to keep the connection open. When changing `KeepAliveInterval`, change the `ServerTimeout` or `serverTimeoutInMilliseconds` setting on the client. The recommended `ServerTimeout` or `serverTimeoutInMilliseconds` value is double the `KeepAliveInterval` value.  |
 | `SupportedProtocols` | All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
 | `EnableDetailedErrors` | `false` | If `true`, detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is `false` because these exception messages can contain sensitive information. |
 | `StreamBufferCapacity` | `10` | The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items.|
@@ -494,4 +494,4 @@ HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/c
 
 [!INCLUDE[](~/signalr/configuration/includes/configuration6.md)]
 
-[!INCLUDE[](~/signalr/configuration/includes/configuration7.md)]
+[!INCLUDE[](~/signalr/configuration/includes/configuration7.md)]