Fix docs explaining the returnPoints argument of convexHull.

modules/imgproc/include/opencv2/imgproc.hpp

@@ -3930,8 +3930,8 @@ to the right, and its Y axis pointing upwards.
 @param returnPoints Operation flag. In case of a matrix, when the flag is true, the function
 returns convex hull points. Otherwise, it returns indices of the convex hull points. When the
 output array is std::vector, the flag is ignored, and the output depends on the type of the
-vector: std::vector\<int\> implies returnPoints=true, std::vector\<Point\> implies
-returnPoints=false.
+vector: std::vector\<int\> implies returnPoints=false, std::vector\<Point\> implies
+returnPoints=true.
  */
 CV_EXPORTS_W void convexHull( InputArray points, OutputArray hull,
                               bool clockwise = false, bool returnPoints = true );