Update fsdp.py

Author: amorehead

src/lightning/pytorch/plugins/precision/fsdp.py

@@ -76,9 +76,6 @@ def __init__(self, precision: _PRECISION_INPUT, scaler: Optional["ShardedGradSca
     @override
     def clip_grad_by_norm(self, *_: Any, **__: Any) -> None:
         # see https://pytorch.org/docs/stable/fsdp.html#torch.distributed.fsdp.FullyShardedDataParallel.clip_grad_norm_
-        # section `Gradient Clipping`, using `torch.nn.utils.clip_grad_norm_` is incorrect with FSDP.
-        # To overcome this we need to call root_sharded_module.clip_grad_norm(clip_val), but we don't have a reference
-        # to the root module
         raise MisconfigurationException(
             f"`gradient_clip_algorithm='norm'` is currently not supported for `{self.__class__.__name__}`"
         )