Docs: Update copyright and remove AUTHORS file

Author: dmethvin

AUTHORS.txt

@@ -1,4 +1,4 @@
-Copyright jQuery Foundation and other contributors, https://jquery.org/
+Copyright OpenJS Foundation and other contributors, https://openjsf.org/
 
 This software consists of voluntary contributions made by many
 individuals. For exact contribution history, see the revision history

LICENSE.txt

@@ -6,8 +6,8 @@
 	"version": "3.0.2-pre",
 	"homepage": "https://github.com/jquery/jquery-migrate",
 	"author": {
-		"name": "jQuery Foundation and other contributors",
-		"url": "https://github.com/jquery/jquery-migrate/blob/master/AUTHORS.txt"
+		"name": "OpenJS Foundation and other contributors",
+		"url": "https://openjsf.org"
 	},
 	"repository": {
 		"type": "git",
@@ -35,7 +35,6 @@
 		"grunt-contrib-uglify": "4.0.1",
 		"grunt-contrib-watch": "1.1.0",
 		"grunt-eslint": "21.0.0",
-		"grunt-git-authors": "3.2.0",
 		"grunt-karma": "3.0.2",
 		"karma": "4.1.0",
 		"karma-browserstack-launcher": "1.5.1",