Update README.md (#13283)

* Update README.md

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

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---------

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>

utils/metrics.py

@@ -100,7 +100,7 @@ def compute_ap(recall, precision):
         recall:    The recall curve (list)
         precision: The precision curve (list)
     # Returns
-        Average precision, precision curve, recall curve
+        Average precision, precision curve, recall curve.
     """
     # Append sentinel values to beginning and end
     mrec = np.concatenate(([0.0], recall, [1.0]))