Improve documentation for setting up the environment to run notebooks. Kickstarting new dev effort on this package

Author: J-M

environment.yml

@@ -0,0 +1,22 @@
+name: DCX
+channels:
+  - oggm
+  - conda-forge
+  - defaults
+dependencies:
+  - dask #=2.3.0=py_0
+  - geopandas #=0.5.1=py_0
+  - ipyleaflet #=0.11.1=py37_1
+  - ipywidgets #=7.5.1=py_0
+  - jupyter #=1.0.0=py_2
+  - jupyterlab #=1.1.1=py_0
+  - matplotlib #=3.1.1=py37_1
+  - netcdf4 #=1.5.1.2=py37h73a1b54_1
+  - pytest #=5.1.2=py37_0
+  - rasterio #=1.0.26=py37hdff7cfa_1
+  - requests #=2.22.0=py37_1
+  - salem #=0.2.4.201906261358=py_0
+  - seaborn #=0.9.0=py_1
+  - siphon #=0.8.0=py37_1001
+  - tqdm #=4.35.0=py_0
+  - xarray #=0.12.3=py_0