Cleanup based on comments by William Rucklidge

Change-Id: If269ba8e388965a8ea32260fd6f17a133a19ab9b
diff --git a/internal/ceres/visibility_based_preconditioner.h b/internal/ceres/visibility_based_preconditioner.h
index 8a09c78..dae4987 100644
--- a/internal/ceres/visibility_based_preconditioner.h
+++ b/internal/ceres/visibility_based_preconditioner.h
@@ -38,7 +38,8 @@
 // documented here can be found in
 //
 // Visibility Based Preconditioning for Bundle Adjustment
-// A. Kushal & S. Agarwal, submitted to CVPR 2012
+// A. Kushal & S. Agarwal, CVPR 2012.
+//
 // http://www.cs.washington.edu/homes/sagarwal/vbp.pdf
 //
 // The two preconditioners share enough code that its most efficient