Update compute description

src/torchmetrics/segmentation/mean_iou.py

@@ -124,7 +124,7 @@ def update(self, preds: Tensor, target: Tensor) -> None:
         self.num_batches += 1
 
     def compute(self) -> Tensor:
-        """Update the state with the new data."""
+        """Compute the final Mean Intersection over Union (mIoU)."""
         return self.score / self.num_batches
 
     def plot(self, val: Union[Tensor, Sequence[Tensor], None] = None, ax: Optional[_AX_TYPE] = None) -> _PLOT_OUT_TYPE: