Denote Teckids e.V. as licensor as defined by EUPL

This is important to clarify the jurisdiction and court location in case of
license disputes.

README.rst

@@ -31,7 +31,7 @@ Licence
   Copyright © 2019 Tom Teichler <tom.teichler@teckids.org>
   Copyright © 2019 Hangzhi Yu <yuha@katharineum.de>
 
-  Licenced under the EUPL, version 1.2 or later
+  Licenced under the EUPL, version 1.2 or later, by Teckids e.V. (Bonn, Germany).
 
 Please see the LICENCE.rst file accompanying this distribution for the
 full licence text or on the `European Union Public Licence`_ website