[docs] Fix typos

Change-Id: I447bd63b58a7bfc7c1df36dbef5dcba454d28256

docs/source/nnls_tutorial.rst

diff --git a/docs/source/nnls_tutorial.rst b/docs/source/nnls_tutorial.rst
index 6c89032..7f7e810 100644
--- a/docs/source/nnls_tutorial.rst
+++ b/docs/source/nnls_tutorial.rst
@@ -355,14 +355,14 @@
 
   Problem problem;
 
-  // Add residual terms to the problem using the using the autodiff
+  // Add residual terms to the problem using the autodiff
   // wrapper to get the derivatives automatically.
   problem.AddResidualBlock(
     new AutoDiffCostFunction<F1, 1, 1, 1>(new F1), nullptr, &x1, &x2);
   problem.AddResidualBlock(
     new AutoDiffCostFunction<F2, 1, 1, 1>(new F2), nullptr, &x3, &x4);
   problem.AddResidualBlock(
-    new AutoDiffCostFunction<F3, 1, 1, 1>(new F3), nullptr, &x2, &x3)
+    new AutoDiffCostFunction<F3, 1, 1, 1>(new F3), nullptr, &x2, &x3);
   problem.AddResidualBlock(
     new AutoDiffCostFunction<F4, 1, 1, 1>(new F4), nullptr, &x1, &x4);
 

examples/powell.cc

diff --git a/examples/powell.cc b/examples/powell.cc
index 7212710..1a09a73 100644
--- a/examples/powell.cc
+++ b/examples/powell.cc
@@ -106,7 +106,7 @@
   double x4 = 1.0;
 
   Problem problem;
-  // Add residual terms to the problem using the using the autodiff
+  // Add residual terms to the problem using the autodiff
   // wrapper to get the derivatives automatically. The parameters, x1 through
   // x4, are modified in place.
   problem.AddResidualBlock(