Moving Kite Dataset API info from old guide per CDK-753.

Link to the old guide from which this came. This is just shards of information brought forward so they're not lost. This info should be woven into the samples before 1.0.

http://kitesdk.org/docs/current/kite-data/guide.html
You bet you can, Sparky! You can also use the DatasetDescriptor.Builder, as I adjusted the text to properly state.