A couple more grammar fixes

README.rst

@@ -58,7 +58,7 @@ Package overview
 * ``gprMax`` is the main package. Within this package, the main module is ``gprMax.py``
 * ``gprMax.toml`` contains build system requirements.
 * ``LICENSE`` contains information on the `GNU General Public License v3 or higher <http://www.gnu.org/copyleft/gpl.html>`_.
-* ``MANIFEST.in`` consists of commands, one per line, instructing setup tools to add or remove files from the source distribution.
+* ``MANIFEST.in`` consists of commands, one per line, instructing setuptools to add or remove files from the source distribution.
 * ``README.rst`` contains getting started information on installation, usage, and new features/changes.
 * ``setup.py`` is the centre of all activity in building, distributing, and installing gprMax, including building and compiling the Cython extension modules.
 * ``testing`` is a sub-package which contains test modules and input files.