Auto merge of #30958 - dhodder:master, r=brson

The COPYRIGHT file should be updated to note that Rust no longer ships with AUTHORS.txt.

    $ git log -1 -- AUTHORS.txt
    commit 402749c
    Author: Brian Anderson <banderson@mozilla.com>
    Date:   Wed Dec 2 22:16:08 2015 +0000

        Remove AUTHORS.txt and add-authors.sh

        Keeping this file up to date requires hours of work every release,
        even with the script. It is a fool's errand and we shall not do it
        any longer.

Author: bors

Diff for: COPYRIGHT

@@ -7,7 +7,7 @@ terms.
 Longer version:
 
 The Rust Project is copyright 2016, The Rust Project
-Developers (given in the file AUTHORS.txt).
+Developers.
 
 Licensed under the Apache License, Version 2.0
 <LICENSE-APACHE or