Fix broken links on install/index.rst

Currently the links in the section summary on the index.rst/index.html
file are broken. Can be reproduced by going to
http://ipython.readthedocs.io/en/stable/install/index.html and clicking
on *installing IPython itself*, or *kernels for Jupyter* links.

Specific changes
----------------
* Added a reference label to the `install.rst` file
* Modified links from external link format to Sphinx arbitrary location
cross-referencing format in the `index.rst` file

Testing
-------
Changes have been tested with a local sphinx build through the supplied
makefile and specific links touched are fixed. Tested a few possibly
overlapping links (Jupyter:install for instance) and they seem to be
unaffected by the change.

docs/source/install/index.rst

@@ -1,58 +1,58 b''
 .. _install_index:
 
 ============
 Installation
 ============
 
 .. toctree::
    :maxdepth: 3
    :hidden:
 
 
    install
    kernel_install
 
 
 
-This sections will guide you through `installing IPython itself <install>`_, and
-installing `kernels for Jupyter <kernel_install>`_ if you wish to work with
+This sections will guide you through :ref:`installing IPython itself <install>`, and
+installing :ref:`kernels for Jupyter <kernel_install>` if you wish to work with
 multiple version of Python, or multiple environments.
 
 
 Quick install reminder
 ~~~~~~~~~~~~~~~~~~~~~~
 
 Here is a quick reminder of the commands needed for installation if you are
 already familiar with IPython and are just searching to refresh your memory:
 
 Install IPython:
 
 .. code-block:: bash
 
     $ pip install ipython
 
 
 Install and register an IPython kernel with Jupyter:
 
 
 .. code-block:: bash
 
     $ python -m pip install ipykernel
 
     $ python -m ipykernel install [--user] [--name <machine-readable-name>] [--display-name <"User Friendly Name">]
 
 for more help see 
 
 .. code-block:: bash
     
     $ python -m ipykernel install  --help
     
 
 
 .. seealso::
 
    `Installing Jupyter <http://jupyter.readthedocs.io/en/latest/install.html>`__
      The Notebook, nbconvert, and many other former pieces of IPython are now
      part of Project Jupyter.
 
 

docs/source/install/install.rst

@@ -1,142 +1,144 b''
+.. _install:
+
 Installing IPython
 ==================
 
 
 IPython requires Python 2.7 or ≥ 3.3.
 
 
 Quick Install 
 -------------
 
 With ``pip`` already installed :
 
 .. code-block:: bash
 
     $ pip install ipython
 
 This installs IPython as well as its dependencies.
 
 If you want to use IPython with notebooks or the Qt console, you should also
 install Jupyter ``pip install jupyter``.
 
 
 
 Overview
 --------
 
 This document describes in detail the steps required to install IPython. For a
 few quick ways to get started with package managers or full Python
 distributions, see `the install page <http://ipython.org/install.html>`_ of the
 IPython website.
 
 Please let us know if you have problems installing IPython or any of its
 dependencies.
 
 IPython and most dependencies should be installed via :command:`pip`.
 In many scenarios, this is the simplest method of installing Python packages.
 More information about :mod:`pip` can be found on
 `its PyPI page <https://pip.pypa.io>`__.
 
 
 More general information about installing Python packages can be found in
 `Python's documentation <http://docs.python.org>`_.
 
 .. _dependencies:
 
 Dependencies
 ~~~~~~~~~~~~
 
 IPython relies on a number of other Python packages. Installing using a package
 manager like pip or conda will ensure the necessary packages are installed.
 Manual installation without dependencies is possible, but not recommended.
 The dependencies can be viewed with package manager commands,
 such as :command:`pip show ipython` or :command:`conda info ipython`.
 
 
 Installing IPython itself
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 IPython requires several dependencies to work correctly, it is not recommended
 to install IPython and all its dependencies manually as this can be quite long
 and troublesome. You should use the python package manager ``pip``.
 
 Installation using pip
 ~~~~~~~~~~~~~~~~~~~~~~
 
 Make sure you have the latest version of :mod:`pip` (the Python package
 manager) installed. If you do not, head to `Pip documentation
 <https://pip.pypa.io/en/stable/installing/>`_ and install :mod:`pip` first.
 
 The quickest way to get up and running with IPython is to install it with pip:
 
 .. code-block:: bash
 
     $ pip install ipython
 
 That's it.
 
 
 Installation from source
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you don't want to use :command:`pip`, or don't have it installed,
 grab the latest stable tarball of IPython `from PyPI
 <https://pypi.python.org/pypi/ipython>`__.  Then do the following:
 
 .. code-block:: bash
 
     $ tar -xzf ipython.tar.gz
     $ cd ipython
     $ pip install .
 
 Do not invoke ``setup.py`` directly as this can have undesirable consequences
 for further upgrades. Try to also avoid any usage of ``easy_install`` that can
 have similar undesirable consequences.
 
 If you are installing to a location (like ``/usr/local``) that requires higher
 permissions, you may need to run the last command with :command:`sudo`. You can
 also install in user specific location by using the ``--user`` flag in
 conjunction with pip.
 
 To run IPython's test suite, use the :command:`iptest` command from outside of
 the IPython source tree:
 
 .. code-block:: bash
 
     $ iptest
 
 .. _devinstall:
 
 Installing the development version
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 It is also possible to install the development version of IPython from our
 `Git <http://git-scm.com/>`_ source code repository.  To do this you will
 need to have Git installed on your system.  
 
 
 Then do:
 
 .. code-block:: bash
 
     $ git clone https://github.com/ipython/ipython.git
     $ cd ipython
     $ pip install -e .
 
 The :command:`pip install -e .` command allows users and developers to follow
 the development branch as it changes by creating links in the right places and
 installing the command line scripts to the appropriate locations.
 
 Then, if you want to update your IPython at any time, do:
 
 .. code-block:: bash
 
     $ git pull
 
 If the dependencies or entrypoints have changed, you may have to run
 
 .. code-block:: bash
 
     $ pip install -e .
 
 again, but this is infrequent.