Update documentation

Author: andersy005

docs/source/index.rst

@@ -3,7 +3,8 @@
 .. toctree::
    :maxdepth: 2
    :caption: Contents:
-
+   
+   installing
    notebooks/overview.ipynb
    notebooks/GLADE-cmip5_database.ipynb
    api

docs/source/installing.rst

@@ -0,0 +1,44 @@
+Installing
+==========
+
+You can install intake-cmip with ``pip``, ``conda``, or by installing from source.
+
+Pip
+---
+
+Pip can be used to install intake-cmip::
+
+   pip install intake-cmip
+
+Conda
+-----
+
+To install the latest version of intake-cmip from the
+`conda-forge <https://conda-forge.github.io/>`_ repository using
+`conda <https://www.anaconda.com/downloads>`_::
+
+    conda install -c conda-forge intake-cmip
+
+Install from Source
+-------------------
+
+To install intake-cmip from source, clone the repository from `github
+<https://github.com/NCAR/intake-cmip>`_::
+
+    git clone https://github.com/NCAR/intake-cmip.git
+    cd intake-cmip
+    pip install .
+
+You can also install directly from git master branch::
+
+    pip install git+https://github.com/NCAR/intake-cmip
+
+
+Test
+----
+
+Test intake-cmip with ``pytest``::
+
+    git clone https://github.com/NCAR/intake-cmip.git
+    cd intake-cmip
+    pytest - v