minor fix to README.md

Author: lukasstadler

README.md

@@ -22,4 +22,4 @@ Universal Permissive License v 1.0 as shown at
 [http://oss.oracle.com/licenses/upl](http://oss.oracle.com/licenses/upl). This
 implementation is in part derived from and contains additional code from 3rd
 parties, the copyrights and licensing of which is detailed in the
-[LICENSE](LICENSE) file.
+[LICENSE](LICENSE) and [3rd_party_licenses.txt](3rd_party_licenses.txt) files.