Resolve "doc: licence information"

Closes #1 (closed)

README.md

-# community-theme
+# Community-theme
+## License
 
+[![community-theme Copyright 2021-present Lydra](https://www.gnu.org/graphics/gplv3-with-text-136x68.png)](https://choosealicense.com/licenses/gpl-3.0/)
+
+**community-theme** is maintained by [Lydra](https://lydra.fr/) and released under the GPL3 license.