videoDimensions or mediaDimensions documentation nuance

[jeffreycarlson]

https://interactiveadvertisingbureau.github.io/SIMID/simid-1.0.1.html#simid-player-resize

dictionary MessageArgs {
  required Dimensions videoDimensions;
  required Dimensions creativeDimensions;
  required boolean fullscreen;
};

dictionary Dimensions {
  required long x;
  required long y;
  required long width;
  required long height;
};
mediaDimensions,
Media element size and coordinates.
creativeDimensions,
SIMID iframe size and coordinates.*
fullscreen,
Value is true when the ad is in fullscreen mode.

Should this be videoDimensions or mediaDimensions?

[wabiloo]

See #292