Update README.md

Author: denismakogon

README.md

@@ -4,7 +4,7 @@ Docker image with python 3.6 and opencv 3.2
 
 Usage:
 
-    docker run -it docker-python3-opencv python
+    docker run -it jjanzic/docker-python3-opencv python
     >>> import cv2
 
 Image tagged with `:contrib` contains docker image built with [contrib modules](https://github.com/opencv/opencv_contrib/)