fix README issues for #44 and add generic notification handler docs (v2.1.2) (#49)

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: hasanxdev <30981174+hasanxdev@users.noreply.github.com>

Author: Copilot

README.md

@@ -31,6 +31,7 @@
     3. Notifications:
         1. `INotification`
         2. `INotificationHandler<TRequestEvent>`
+        3. Open-generic `INotificationHandler<TNotification> where TNotification : INotification`
 > :bulb: **Tip:** *If you're looking for a mediator with the raw performance of hand-written code, DispatchR is built for you.*
 
 ## ✨ How to install?
@@ -62,6 +63,9 @@ public sealed class PingMediatR : IRequest<int> { }
 public sealed class PingDispatchR : IRequest<PingDispatchR, ValueTask<int>> { } 
 ```
 
+> [!IMPORTANT]
+> Always use a **generic** return type such as `Task<TResult>` or `ValueTask<TResult>`. Using a bare `Task` or `ValueTask` (without a type argument) may prevent the handler from being triggered when pipeline behaviors or validators are present.
+
 ## Handler Definition
 
 ### MediatR
@@ -152,7 +156,7 @@ public sealed class CounterStreamRequestMediatR : IStreamRequest<int> { }
 1. Sending `TRequest` to `IStreamRequest`
 
 ```csharp
-public sealed class CounterStreamRequestDispatchR : IStreamRequest<PingDispatchR, ValueTask<int>> { } 
+public sealed class CounterStreamRequestDispatchR : IStreamRequest<CounterStreamRequestDispatchR, int> { } 
 ```
 
 ## Stream Handler Definition
@@ -171,9 +175,9 @@ public sealed class CounterStreamHandlerMediatR : IStreamRequestHandler<CounterS
 ### Stream Handler DispatchR (Don't change)
 
 ```csharp
-public sealed class CounterStreamHandlerDispatchR : IStreamRequestHandler<CounterStreamHandlerDispatchR, int>
+public sealed class CounterStreamHandlerDispatchR : IStreamRequestHandler<CounterStreamRequestDispatchR, int>
 {
-    public async IAsyncEnumerable<int> Handle(CounterStreamHandlerDispatchR request, CancellationToken cancellationToken)
+    public async IAsyncEnumerable<int> Handle(CounterStreamRequestDispatchR request, CancellationToken cancellationToken)
     {
         yield return 1;
     }
@@ -248,7 +252,7 @@ public sealed class EventHandler(ILogger<Event> logger) : INotificationHandler<E
 }
 ```
 
-### Stream Pipeline DispatchR
+### Notification DispatchR
 1. Use ___ValueTask___
 
 ```csharp
@@ -264,6 +268,23 @@ public sealed class EventHandler(ILogger<Event> logger) : INotificationHandler<E
 }
 ```
 
+#### Generic notification handler DispatchR
+1. A single open-generic handler receives **every** notification type — ideal for cross-cutting concerns such as logging, auditing, or telemetry.
+
+```csharp
+public sealed class AllNotificationsLogger<TNotification>(ILogger<AllNotificationsLogger<TNotification>> logger)
+    : INotificationHandler<TNotification>
+    where TNotification : INotification
+{
+    public ValueTask Handle(TNotification notification, CancellationToken cancellationToken)
+    {
+        logger.LogInformation("[Generic] Received notification of type {NotificationType}: {@Notification}",
+            typeof(TNotification).Name, notification);
+        return ValueTask.CompletedTask;
+    }
+}
+```
+
 # ⚡ How DispatchR Achieves High Performance
 
 ###### DispatchR is designed with one goal in mind: **maximize performance with minimal memory usage**. Here's how it accomplishes that: