Minor fix to tutorial.rst

Change-Id: Idb4408dedf81ff96732b27b4e04cbaed9f257bf4

docs/source/tutorial.rst

diff --git a/docs/source/tutorial.rst b/docs/source/tutorial.rst
index bad5039..3329927 100644
--- a/docs/source/tutorial.rst
+++ b/docs/source/tutorial.rst
@@ -205,7 +205,7 @@
       new AutoDiffCostFunction<CostFunctor, 1, 1>(new CostFunctor);
   problem.AddResidualBlock(cost_function, NULL, &x);
 
-The construction looks almost identical to the used for automatic
+The construction looks almost identical to the one used for automatic
 differentiation, except for an extra template parameter that indicates
 the kind of finite differencing scheme to be used for computing the
 numerical derivatives [#f3]_. For more details see the documentation