Update README.md

re-license under Apache2.0

Author: Dzmitry Humianiuk

README.md

@@ -127,5 +127,5 @@ service.terminate()
 
 # Copyright Notice
 
-Licensed under the [GPLv3](https://www.gnu.org/licenses/quick-guide-gplv3.html)
+Licensed under the [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0)
 license (see the LICENSE.txt file).