Added dask to scipy-notebook doc

Author: romainx

docs/using/selecting.md

@@ -76,7 +76,7 @@ packages from [conda-forge](https://conda-forge.github.io/feedstocks)
 `jupyter/scipy-notebook` includes popular packages from the scientific Python ecosystem.
 
 * Everything in `jupyter/minimal-notebook` and its ancestor images
-* [pandas](https://pandas.pydata.org/), [numexpr](https://github.com/pydata/numexpr), [matplotlib](https://matplotlib.org/), [scipy](https://www.scipy.org/),
+* [dask](https://dask.org/), [pandas](https://pandas.pydata.org/), [numexpr](https://github.com/pydata/numexpr), [matplotlib](https://matplotlib.org/), [scipy](https://www.scipy.org/),
 [seaborn](https://seaborn.pydata.org/), [scikit-learn](http://scikit-learn.org/stable/), [scikit-image](http://scikit-image.org/),
 [sympy](http://www.sympy.org/en/index.html), [cython](http://cython.org/), [patsy](https://patsy.readthedocs.io/en/latest/),
 [statsmodel](http://www.statsmodels.org/stable/index.html), [cloudpickle](https://github.com/cloudpipe/cloudpickle), [dill](https://pypi.python.org/pypi/dill),