Fix an incorrect usage message in bundle_adjuster.cc

Change-Id: I66889ac8e52dd3baaee9e80cb04b7a8575537249

examples/bundle_adjuster.cc

diff --git a/examples/bundle_adjuster.cc b/examples/bundle_adjuster.cc
index 696aa58..985dbaf 100644
--- a/examples/bundle_adjuster.cc
+++ b/examples/bundle_adjuster.cc
@@ -348,7 +348,7 @@
   CERES_GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
   google::InitGoogleLogging(argv[0]);
   if (FLAGS_input.empty()) {
-    LOG(ERROR) << "Usage: bundle_adjustment_example --input=bal_problem";
+    LOG(ERROR) << "Usage: bundle_adjuster --input=bal_problem";
     return 1;
   }