Add documentation in Random.js about where the seeds come from

[samreid]

@pixelzoom recommended to add documentation in Random.js about where the seeds come from. Marking as high priority to add to my todo list.

[samreid]

The documentation for the random seeds currently reads:

    options = _.extend( {

      // {number|null} seed for the random number generator.  When seed is null, Math.random() is used.
      seed: null,

      // {boolean} if true, use the seed specified statically in `phet.chipper.randomSeed`.  This value is declared
      // in initialize-globals.js and can be overriden by PhET-iO for reproducible playback (see TPhETIO.setRandomSeed).
      staticSeed: false

    }, options );

I'm unsure what to add. @pixelzoom can you please help?

[pixelzoom]

Looks good. Closing.