Add license statements in README.md

Author: sunglok

README.md

@@ -7,8 +7,8 @@ _An Invitation to 3D Vision_ is a introductory tutorial on 3D vision (a.k.a. vis
  * Download binaries and headers for [OpenCV][] and [CLAPACK][] for Windows [Link](https://github.com/sunglok/3dv_tutorial/releases/download/misc/EXTERNAL4Windows.32bit.zip)
 
 ### What does its name come from?
- * The tutorial title, _An Invitation to 3D Vision_, came from [a legendary book by Yi Ma, Stefano Soatto, Jana Kosecka, and Shankar S. Sastry](http://vision.ucla.edu/MASKS/). We wish that this tutorial will be the first gentle invitation card for beginners in 3D vision and explorers from other fields.
- * The subtitle, _for everyone_, came from [Prof. Kim's online lecture](https://hunkim.github.io/ml/) (in Korean). This tutorial is also intended not only for students and researchers in academia, but also for hobbyists and developers in industries. We tried to describe important and typical problems and their solutions in [OpenCV][]. We hope readers understand it easily without serious mathematical background.
+ * The main title, _An Invitation to 3D Vision_, came from [a legendary book by Yi Ma, Stefano Soatto, Jana Kosecka, and Shankar S. Sastry](http://vision.ucla.edu/MASKS/). We wish that our tutorial will be the first gentle invitation card for beginners in 3D vision and explorers from other fields.
+ * The subtitle, _for everyone_, came from [Prof. Kim's online lecture](https://hunkim.github.io/ml/) (in Korean). Our tutorial is also intended not only for students and researchers in academia, but also for hobbyists and developers in industries. We tried to describe important and typical problems and their solutions in [OpenCV][]. We hope readers understand it easily without serious mathematical background.
 
 ### Example descriptions
  * __Single-view Geometry__
@@ -37,7 +37,7 @@ _An Invitation to 3D Vision_ is a introductory tutorial on 3D vision (a.k.a. vis
  * [OpenCV][] (> 3.0.0, 3-clause BSD License)
   * _OpenCV_ is a base of all example codes for linear algebra, vision algorithms, image/video manipulation, and GUI.
  * [cvsba][] (GPL): An OpenCV wrapper for sba library
-  * _cvsba_ is used by bundle adjustment and already included in EXTERNAL directory. It is optional for bundle adjustment.
+  * _cvsba_ is used by bundle adjustment. It is optional for bundle adjustment but included in EXTERNAL directory in the sake of your convenience.
  * [CLAPACK][] (Public Domain): f2c'ed version of LAPACK
   * _CLAPACK_ is used by cvsba. It is optional for bundle adjustment.
 
@@ -48,6 +48,9 @@ The authors thank the following contributors and projects.
  * [Kang Li](http://www.cs.cmu.edu/~kangli/code/Image_Stabilizer.html): We include his traffic video for demonstrating video stabilization.
  * [Dr. Jae-Yeong Lee](https://sites.google.com/site/roricljy/): We sincerely thank him for motivating many examples and providing [OpenCV][] binaries for Windows.
 
+### License
+ * [Beerware](http://en.wikipedia.org/wiki/Beerware)
+
 ### Contact
  * [Sunglok Choi](http://sites.google.com/site/sunglok/) (sunglok AT hanmail DOT net)