Update README.md

Author: gempa-jabe

README.md

@@ -8,7 +8,7 @@ SeisComP3 is distributed under the [SeisComP Public License](COPYING)
 
 > - The purpose of this repository is to test upcoming features and to
 >   integrate community source code and patches
-> - For production systems only use the official releases from http://www.seiscomp3.org
+> - For production systems only use the official releases from http://www.seiscomp3.org or the corresponding tags in this repository.
 > - Commercial modules obtained from [gempa GmbH](http://www.gempa.de) are only
 >   available for official releases. Binary compatibility of intermediate
 >   SeisComP3 versions is not guaranteed.