Implement all missing docstrings (#5298)

Co-authored-by: snyk-bot <snyk-bot@snyk.io>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/models/nas/val.py

@@ -9,6 +9,30 @@ __all__ = ['NASValidator']
 
 
 class NASValidator(DetectionValidator):
+    """
+    Ultralytics YOLO NAS Validator for object detection.
+
+    Extends `DetectionValidator` from the Ultralytics models package and is designed to post-process the raw predictions
+    generated by YOLO NAS models. It performs non-maximum suppression to remove overlapping and low-confidence boxes,
+    ultimately producing the final detections.
+
+    Attributes:
+        args (Namespace): Namespace containing various configurations for post-processing, such as confidence and IoU thresholds.
+        lb (torch.Tensor): Optional tensor for multilabel NMS.
+
+    Example:
+        ```python
+        from ultralytics import NAS
+
+        model = NAS('yolo_nas_s')
+        validator = model.validator
+        # Assumes that raw_preds are available
+        final_preds = validator.postprocess(raw_preds)
+        ```
+
+    Note:
+        This class is generally not instantiated directly but is used internally within the `NAS` class.
+    """
 
     def postprocess(self, preds_in):
         """Apply Non-maximum suppression to prediction outputs."""