Bump up to v2.3 (#34)

Author: DefTruth

README.md

@@ -5,7 +5,7 @@
   <img src=https://img.shields.io/github/watchers/DefTruth/cuda-learn-note?color=9cc >
   <img src=https://img.shields.io/github/forks/DefTruth/cuda-learn-note.svg?style=social >
   <img src=https://img.shields.io/github/stars/DefTruth/cuda-learn-note.svg?style=social >
-  <img src=https://img.shields.io/badge/Release-v2.2-brightgreen.svg >
+  <img src=https://img.shields.io/badge/Release-v2.3-brightgreen.svg >
   <img src=https://img.shields.io/badge/License-GPLv3.0-turquoise.svg >
  </div>