adding short explainers for index pages
MODIFY
docs/source/configuration/index.rst
docs/source/configuration/index.rst
Configuring your repository
===========================
+Information about configuring your repository to work with repo2docker,
+and controlling elements of the built environment using configuration files.
+
.. toctree::
:maxdepth: 2
:caption: Complete list of configuration files

MODIFY
docs/source/contributing/index.rst
docs/source/contributing/index.rst
Contributing
============
+The repo2docker community is welcoming of all kinds of help and
+participation from others. Below are a few ways that you can get involved,
+as well as resources for understanding the structure and design of the
+repo2docker package.
+
.. toctree::
contributing

MODIFY
docs/source/getting-started/index.rst
docs/source/getting-started/index.rst
Getting Started
===============
+Instructions and information on how to get started with repo2docker
+on your own machine. Select from the pages listed below to begin.
+
.. toctree::
:maxdepth: 2
- :caption: Getting started with repo2docker
../install
../usage

MODIFY
docs/source/howto/index.rst
docs/source/howto/index.rst
@@ -3,6 +3,7 @@ How-to Guides
=============
Short, actionable guides that cover specific topics with repo2docker.
+Select from the pages listed below to get started.
.. toctree::
:maxdepth: 2

adding short explainers for index pages