Merge pull request #122 from poldracklab/docs/installation

DOC: Add an *Installation* section

Author: oesteban

docs/index.rst

@@ -51,5 +51,6 @@ Contents
 .. toctree::
     :maxdepth: 3
 
+    installation
+    changes
     api
-    changes

docs/installation.rst

@@ -0,0 +1,30 @@
+Installation
+============
+*NiTransforms* is distributed via *Pypi* and can easily be installed
+within your Python distribution with::
+
+  python -m pip install nitransforms
+
+Alternatively, you can install the bleeding-edge version of the software
+directly from the GitHub repo with::
+
+  python -m pip install git+https://github.com/poldracklab/nitransforms.git@master
+
+To verify the installation, you can run the following command::
+
+  python -c "import nitransforms as nt; print(nt.__version__)"
+
+You should see the version number.
+
+Developers
+----------
+Advanced users and developers who plan to contribute with bugfixes, documentation,
+etc. can first clone our Git repository::
+
+  git clone https://github.com/poldracklab/nitransforms.git
+
+
+and install the tool in *editable* mode::
+
+  cd nitransforms
+  python -m pip install -e .