Update profiler.rst

Author: KAVYANSHTYAGI

docs/source-pytorch/tuning/profiler.rst

@@ -11,6 +11,19 @@ Find bottlenecks in your code
 
 .. Add callout items below this line
 
+.. warning::
+
+    Do **not** wrap ``Trainer.fit()``, ``Trainer.validate()``, or similar Trainer methods inside a manual ``torch.profiler.profile`` context manager.
+    This will cause unexpected crashes and cryptic errors due to incompatibility between PyTorch Profiler's context and Lightning's training loop.
+    Instead, use the ``profiler`` argument of the ``Trainer``:
+
+    .. code-block:: python
+
+        trainer = pl.Trainer(
+            profiler="pytorch",  # This is the correct and supported way
+            ...
+        )
+
 .. displayitem::
    :header: Basic
    :description: Learn to find bottlenecks in the training loop.