Xgboost: QUESTION: adding Dask in repo description

[jameslamb]

I've been thinking about https://github.com/dask/community/issues/104 a lot the last few days, and I'd like to propose a small change that I think could help communication about XGBoost's support for Dask.

Given that xgboost.dask has been a part of the project for a while, would you consider adding Dask to the repo description, in the list where Spark and Flink are already mentioned?

[trivialfis]

Oops. Mentioned it in readme but forgot the repo description. Thanks for reminding.

[hcho3]

I've added Dask to the repo description. Thanks!