fix argument description for on_train_batch callbacks in LambdaCallback (#21464)

Author: sonali-kumari1

keras/src/callbacks/lambda_callback.py

@@ -14,8 +14,8 @@ class LambdaCallback(Callback):
       `epoch`, `logs`
     - `on_train_begin` and `on_train_end` expect one positional argument:
       `logs`
-    - `on_train_batch_begin` and `on_train_batch_end` expect two positional
-      arguments: `batch`, `logs`
+    - `on_train_batch_begin` and `on_train_batch_end` expect a positional
+      argument `batch` and a keyword argument `logs`
     - See `Callback` class definition for the full list of functions and their
       expected arguments.