Fix another typo in Using the SurfaceTool (#5612)

tutorials/3d/procedural_geometry/surfacetool.rst

@@ -22,7 +22,7 @@ Attributes are added before each vertex is added:
     st.add_normal() # Normal never added to a vertex.
 
 When finished generating your geometry with the :ref:`SurfaceTool <class_surfacetool>`
-call ``commit()`` to finished generating the mesh. If an :ref:`ArrayMesh <class_ArrayMesh>` is passed
+call ``commit()`` to finish generating the mesh. If an :ref:`ArrayMesh <class_ArrayMesh>` is passed
 to ``commit()`` then it appends a new surface to the end of the ArrayMesh. While if nothing is passed
 in, ``commit()`` returns an ArrayMesh.