Update GitHub repo location letsencrypt -> certbot (#9713)

* Update GitHub repo location letsencrypt -> certbot

* Revert changes to CHANGELOG

letstest/README.md

@@ -50,4 +50,4 @@ See:
 - https://docs.aws.amazon.com/cli/latest/userguide/cli-ec2-keypairs.html
 
 Main repos:
-- https://github.com/letsencrypt/letsencrypt
+- https://github.com/certbot/certbot

letstest/letstest/multitester.py

@@ -58,17 +58,17 @@ parser.add_argument('test_script',
                     default='test_apache2.sh',
                     help='path of bash script in to deploy and run')
 parser.add_argument('--repo',
-                    default='https://github.com/letsencrypt/letsencrypt.git',
+                    default='https://github.com/certbot/certbot.git',
                     help='certbot git repo to use')
 parser.add_argument('--branch',
                     default='~',
                     help='certbot git branch to trial')
 parser.add_argument('--pull_request',
                     default='~',
-                    help='letsencrypt/letsencrypt pull request to trial')
+                    help='certbot/certbot pull request to trial')
 parser.add_argument('--merge_master',
                     action='store_true',
-                    help="if set merges PR into master branch of letsencrypt/letsencrypt")
+                    help="if set merges PR into master branch of certbot/certbot")
 parser.add_argument('--saveinstances',
                     action='store_true',
                     help="don't kill EC2 instances after run, useful for debugging")