Make pandas-gbq optional dependency consistent with others in the list.

Author: tswast

doc/source/install.rst

@@ -259,7 +259,8 @@ Optional Dependencies
   `xsel <http://www.vergenet.net/~conrad/software/xsel/>`__, or
   `xclip <https://github.com/astrand/xclip/>`__: necessary to use
   :func:`~pandas.read_clipboard`. Most package managers on Linux distributions will have ``xclip`` and/or ``xsel`` immediately available for installation.
-* For Google BigQuery I/O - see `here <https://pandas-gbq.readthedocs.io/en/latest/install.html#dependencies>`__
+* `pandas-gbq <https://pandas-gbq.readthedocs.io/en/latest/install.html#dependencies>`__: for Google BigQuery I/O.
+
 
 * `Backports.lzma <https://pypi.python.org/pypi/backports.lzma/>`__: Only for Python 2, for writing to and/or reading from an xz compressed DataFrame in CSV; Python 3 support is built into the standard library.
 * One of the following combinations of libraries is needed to use the