Small grammar fix in tool recommendations (pypa#287)

Author: adamjstewart

source/current.rst

@@ -15,7 +15,7 @@ Installation Tool Recommendations
 =================================
 
 * Use :ref:`pip` to install Python :term:`packages <Distribution Package>` from
-  :term:`PyPI <Python Package Index (PyPI)>`. [1]_ [2]_ Depending how :ref:`pip`
+  :term:`PyPI <Python Package Index (PyPI)>`. [1]_ [2]_ Depending on how :ref:`pip`
   is installed, you may need to also install :ref:`wheel` to get the benefit
   of wheel caching. [3]_