Corrected some grammar.

README.rst

@@ -38,7 +38,7 @@ Software structure
         user_models/
 
 
-* ``conda_env.yml`` is a configuration file for Anaconda (Miniconda) that setups a Python environment with all the required Python packages for gprMax.
+* ``conda_env.yml`` is a configuration file for Anaconda (Miniconda) that sets up a Python environment with all the required Python packages for gprMax.
 * ``docs`` contains source files for the User Guide. The User Guide is written using reStructuredText (http://docutils.sourceforge.net/rst.html) markup, and is built using Sphinx (http://sphinx-doc.org) and Read the Docs (https://readthedocs.org).
 * ``gprMax`` is the main package. Within this package the main module is ``gprMax.py``
 * ``LICENSE`` contains information on the GNU General Public License v3 or higher (http://www.gnu.org/copyleft/gpl.html).