calculator name has pluralized, updating docs. (#818)

Co-authored-by: Jen Person <[email protected]>

Author: GantMan

pose-detection/README.md

@@ -86,7 +86,8 @@ Example output:
 
 For the `keypoints`, x and y represent the actual keypoint position in the image.
 If you need normalized keypoint positions, you can use the method
-`poseDetection.calculator.keypointsToNormalizedKeypoints(keypoints, imageSize)` to
+`poseDetection.calculators.keypointsToNormalizedKeypoints(keypoints, imageSize)` to
+
 convert x and y to [0, 1] range.
 
 For the `keypoints3D`, x, y and z represent absolute distance in meters in a