fix some spelling errors

Author: baperry2

Docs/sphinx/Spray.rst

@@ -388,7 +388,7 @@ The modified procedure for Manifold-based gas phase chemistry is as follows for
 
 #. Again, :math:`\mu_r`, :math:`\lambda_r`, and :math:`\rho D_{r,n}`  are computed as functions of the manifold :math:`\phi(\xi_j))`.
 
-#. Diffusion coefficent modification proceeds as in the detailed chemistry case.
+#. Diffusion coefficient modification proceeds as in the detailed chemistry case.
 
 #. Momentum source term computation proceeds as in the detailed chemistry case.