* etc/NEWS: Update copyright year.

Author: eggert

etc/NEWS

@@ -1,6 +1,6 @@
 GNU Emacs NEWS -- history of user-visible changes.
 
-Copyright (C) 2017-2019 Free Software Foundation, Inc.
+Copyright (C) 2017-2020 Free Software Foundation, Inc.
 See the end of the file for license conditions.
 
 Please send Emacs bug reports to '[email protected]'.