Update index.rst

added link to paper.

Maybe there can eb new page with publications

Author: dacoex

docs/sphinx/source/index.rst

@@ -38,7 +38,7 @@ Please see our
 `PVSC 2014 paper <http://energy.sandia.gov/wp/wp-content/gallery/uploads/PV_LIB_Python_final_SAND2014-18444C.pdf>`_
 and
 `PVSC 2015 abstract <https://github.com/UARENForecasting/pvlib-pvsc2015/blob/master/pvlib_pvsc_42.pdf?raw=true>`_ 
-for more information.
+(and the `final paper <https://github.com/pvlib/pvsc2015>`_) for more information.
 
 Installation
 ============