update readme (license and release)

Readme.md

+
+[![License](https://img.shields.io/badge/License-GNU%20AGPL%20V3-green.svg?style=flat)](http://www.gnu.org/licenses/agpl-3.0.ru.html) ![Release](https://img.shields.io/badge/Release-v4.0.0-blue.svg?style=flat)
+
 ## Project Information
 
 Official website: [http://www.onlyoffice.org](http://onlyoffice.org "http://www.onlyoffice.org")
@@ -11,3 +14,7 @@ SaaS version: [http://www.onlyoffice.com](http://www.onlyoffice.com "http://www.
 If you have any problems with or questions about this image, please contact us through a [dev.onlyoffice.org][1].
 
   [1]: http://dev.onlyoffice.org
+  
+## License
+
+Core is released under an GNU AGPL v3.0 license. See the LICENSE file for more information.