Move install_arch and fetch-borg-keys playbooks to tasks subdir

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/install-arch.yml -l $host`.
+run the provisioning script: `ansible-playbook playbooks/tasks/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.