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
This can be outside the try block and it is generally best practice to exclude everything you can from the try/finally. The writer just needs to be initialized and used within a try/finally. Speaking of initialization, it doesn't look like it is initialized. I think the descriptor building should be replaced with loading a Dataset, then calling newWriter on it inside the try block.

Nit: the extra line after try isn't typically added.