Note fire-and-forget status of HubConnection event tasks (#57779)

src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs

@@ -97,6 +97,8 @@ public partial class HubConnection : IAsyncDisposable
     /// If this event was triggered from a connection error, the <see cref="Exception"/> that occurred will be passed in as the
     /// sole argument to this handler. If this event was triggered intentionally by either the client or server, then
     /// the argument will be <see langword="null"/>.
+    ///
+    /// The <see cref="Task"/> result does not block <see cref="HubConnection"/> operations.
     /// </remarks>
     /// <example>
     /// The following example attaches a handler to the <see cref="Closed"/> event, and checks the provided argument to determine
@@ -123,6 +125,8 @@ public partial class HubConnection : IAsyncDisposable
     /// </summary>
     /// <remarks>
     /// The <see cref="Exception"/> that occurred will be passed in as the sole argument to this handler.
+    ///
+    /// The <see cref="Task"/> result does not block <see cref="HubConnection"/> operations.
     /// </remarks>
     /// <example>
     /// The following example attaches a handler to the <see cref="Reconnecting"/> event, and checks the provided argument to log the error.
@@ -141,6 +145,8 @@ public partial class HubConnection : IAsyncDisposable
     /// </summary>
     /// <remarks>
     /// The <see cref="string"/> parameter will be the <see cref="HubConnection"/>'s new ConnectionId or null if negotiation was skipped.
+    ///
+    /// The <see cref="Task"/> result does not block <see cref="HubConnection"/> operations.
     /// </remarks>
     /// <example>
     /// The following example attaches a handler to the <see cref="Reconnected"/> event, and checks the provided argument to log the ConnectionId.