Remove ipyparallel docs

These now live in the ipyparallel repo

There are a couple of dangling references from whatsnew entries (to
parallel_overview and parallel_db). These will be fixed once the
parallel docs are built and we can link to them with intersphinx.

docs/source/index.rst

@@ -1,39 +1,38 b''
 =====================
 IPython Documentation
 =====================
 
 .. htmlonly::
 
    :Release: |release|
    :Date: |today|
 
 .. only:: not rtd
 
     Welcome to the official IPython documentation.
 
 .. only:: rtd
 
     This is a partial copy of IPython documentation, please visit `IPython official documentation <http://ipython.org/documentation.html>`_.
 
 Contents
 ========
 
 .. toctree::
    :maxdepth: 1
 
    overview
    whatsnew/index
    install/index
    interactive/index
    notebook/index
-   parallel/index
    config/index
    development/index
    api/index
    about/index
 
 .. htmlonly::
    * :ref:`genindex`
    * :ref:`modindex`
    * :ref:`search`
 

docs/source/parallel/index.rst

@@ -1,7 +1,9 b''
+:orphan:
+
 .. _parallel_index:
 
 ====================================
 Using IPython for parallel computing
 ====================================
 
 IPython.parallel has moved to `ipyparallel <https://github.com/ipython/ipyparallel>`_.