Expand installation doc (#27)

* Fix broken dask_array_type import

* Expand installation doc

Author: kadykov

README.md

@@ -15,8 +15,19 @@ Interface for using cupy in xarray, providing convenience accessors.
 
 ## Installation
 
+From anaconda:
 ```console
-$ pip install git+https://github.com/xarray-contrib/cupy-xarray.git
+conda install cupy-xarray -c conda-forge
+```
+
+From PyPI:
+```console
+pip install cupy-xarray
+```
+
+The latest version from Github:
+```console
+pip install git+https://github.com/xarray-contrib/cupy-xarray.git
 ```
 
 ## Usage