Fix certbot renewal.

.ebextensions/21-certbot.config

@@ -19,10 +19,9 @@
 #
 # commands:
 #   "01-certbot":
-#     test: test ! -f /opt/certbot.done
+#     test: test ! -f /usr/local/bin/certbot
 #     command: |
 #       pip3 install certbot
-#       touch /opt/certbot.done
 #
 # files:
 #   /opt/certbot-renew:
@@ -33,7 +32,7 @@
 #       #!/bin/bash -e
 #       # Sleep randomly, up to 10 minutes, to make it less likely that two servers try to renew at the same time
 #       sleep $(($RANDOM%600))
-#       certbot renew --debug
+#       /usr/local/bin/certbot renew --debug
 #       # Reload the nginx configuration every time, since there may be multiple servers running. Using --renew-hook would only reload nginx on the server that made the renewal.
 #       systemctl reload nginx.service
 #