Fix CameraServer on the roboRIO Python example cutting out robotInit from snippet.

[chrissmith107]

The Advanced Camera Server Program example in Python cuts out the last couple lines from the linked robot.py example, so it isn't complete. This just expands the snippet to include those two missing lines so the example is correct.

Before

import wpilib


class MyRobot(wpilib.TimedRobot):
    """
    This is a demo program showing the use of OpenCV to do vision processing. The image is acquired
    from the USB camera, then a rectangle is put on the image and sent to the dashboard. OpenCV has
    many methods for different types of processing.
    """

After

import wpilib


class MyRobot(wpilib.TimedRobot):
    """
    This is a demo program showing the use of OpenCV to do vision processing. The image is acquired
    from the USB camera, then a rectangle is put on the image and sent to the dashboard. OpenCV has
    many methods for different types of processing.
    """

    def robotInit(self):
        wpilib.CameraServer.launch("vision.py:main")