Update trainer.py

Author: KAVYANSHTYAGI

src/lightning/pytorch/trainer/trainer.py

@@ -264,6 +264,14 @@ def __init__(
             profiler: To profile individual steps during training and assist in identifying bottlenecks.
                 Default: ``None``.
 
+                .. note::
+                    Do **not** use a manual ``torch.profiler.profile`` context manager around
+                    ``Trainer.fit()``, ``Trainer.validate()``, etc.
+                    This will lead to internal errors and cryptic crashes due to incompatibility between
+                    PyTorch Profiler and Lightning's training loop.
+                    Always use this ``profiler`` argument to enable profiling in Lightning.
+
+
             detect_anomaly: Enable anomaly detection for the autograd engine.
                 Default: ``False``.