doc fix

modules/features2d/doc/common_interfaces_of_descriptor_extractors.rst

@@ -66,7 +66,7 @@ Computes the descriptors for a set of keypoints detected in an image (first vari
 
     :param keypoints: Input collection of keypoints. Keypoints for which a descriptor cannot be computed are removed. Sometimes new keypoints can be added, for example: ``SIFT`` duplicates keypoint with several dominant orientations (for each orientation).
 
-    :param descriptors: Computed descriptors. In the second variant of the method ``descriptors[i]`` are descriptors computed for a ``keypoints[i]`. Row ``j`` is the ``keypoints`` (or ``keypoints[i]``) is the descriptor for keypoint ``j``-th keypoint.
+    :param descriptors: Computed descriptors. In the second variant of the method ``descriptors[i]`` are descriptors computed for a ``keypoints[i]``. Row ``j`` is the ``keypoints`` (or ``keypoints[i]``) is the descriptor for keypoint ``j``-th keypoint.
 
 
 DescriptorExtractor::create