Fix small additional typo

examples/step-66/doc/intro.dox

@@ -130,7 +130,7 @@ use of the member functions FEValuesBase::get_function_values() and
 FEValuesBase::get_function_gradients(). This is how step-15, for
 example, does things.
 The <code>assemble_system()</code>
-function would then looks like:
+function would then look like:
 @code
 template <int dim>
 void GelfandProblem<dim>::assemble_system()