readme: update copyright
@@ -4,6 +4,7 @@ libre README
libre is a Generic library for real-time communications with async IO support.
Copyright (C) 2010 - 2020 Creytiv.com
+Copyright (C) 2021 Baresip Foundation (https://github.com/baresip)
![Build](https://github.com/baresip/re/workflows/Build/badge.svg)
![ccheck](https://github.com/baresip/re/workflows/ccheck/badge.svg)
