Update README regarding installation and certbot

Signed-off-by: Florian Pritz <bluewind@xinu.at>

README.md

@@ -7,7 +7,7 @@ It also contains git submodules so you have to run `git submodule update --init
 
 #### Instructions
 All systems are set up the same way. For the first time setup in the Hetzner rescue system,
-run the provisioning script: `ansible-playbook playbooks/$hostname-provision.yml`.
+run the provisioning script: `ansible-playbook playbooks/install-arch.yml -l $host`.
 The provisioning script configures a sane basic systemd with sshd. By design, it is NOT idempotent.
 After the provisioning script has run, it is safe to reboot.
 
@@ -22,6 +22,8 @@ it is necessary to run the following once:
 
     certbot certonly --email webmaster@archlinux.org --agree-tos --rsa-key-size 4096 --renew-by-default --webroot -w /var/lib/letsencrypt/ -d <domain-name>
 
+Note that some roles already run this automatically.
+
 ##### Note about opendkim
 
 The opendkim DNS data has to be added to DNS manually. The roles verifies that the DNS is correct before starting opendkim.