[robocup-legged] Challenge Rules Update

[Michael Quinlan]

Hi,  The rules for the challenges have been updated to reflect some
comments/feedback from local opens.

The full document can be downloaded from the league website, a summary 
of the changes are:

Passing Challenge
     - The robots will be given a text file that contains the location of
the centre of the circles.
     - The robots are allowed to `ball hold' when the ball is not in the
circle. This allows a robot to retrieve a ball and return to the circle
to begin a pass.
     - Slightly modified scoring

The referee will give the benefit of the doubt to the robot. If it is
unclear whether the robot/ball is in or out of the circle (i.e. close to
the line) then the robot/ball will be regarded as inside the circle.

New Goal Challenge
     - Changed the dimensions of the goals
     - Added an extra stationary opponent.

Michael