Update readme

Author: janza

README.md

@@ -1,6 +1,6 @@
 [![Docker Automated buil](https://img.shields.io/docker/automated/jjanzic/docker-python3-opencv.svg)]()
 
-Docker image with python 3.6 and opencv 3.3
+Docker image with python 3.6 and opencv 3.4
 
 Usage:
 
@@ -11,7 +11,9 @@ Image tagged with `:contrib` contains docker image built with [contrib modules](
 
 List of available docker tags:
 
-- `opencv-3.3.0` (`latest`)
-- `contrib-opencv-3.3.0` (`contrib`)
+- `opencv-3.4.0` (`latest` branch)
+- `contrib-opencv-3.4.0` (`contrib` branch)
+- `opencv-3.3.0`
+- `contrib-opencv-3.3.0`
 - `opencv-3.2.0`
 - `contrib-opencv-3.2.0`