update via Conference Steering Committee

very pleased to see the mission of the `Conference Steering Committee` is expanded on [amianet.org](http://www.amianet.org/node/1619). This offers a lot of clarification from the prior mission statement at the end of the [Conference Committee](http://www.amianet.org/node/142).

This clarifies a few things that should be updated in the chart including that the CSC includes the members of CS `chairs` and not general members of the CS.