install_arch: verify bootstrap image signature

Fixes #458 (closed).

roles/install_arch/tasks/main.yml

@@ -9,7+9,7 @@
 
 - name: Prepare Equinix Metal rescue system
   when: ansible_facts['os_family'] == "Alpine"
   block:
     - name: Make sure all required packages are installed in the rescue system
       apk: name=sgdisk,btrfs-progs,tar,gnupg update_cache=yes
 
@@ -44,7+44,7 @@
   when: filesystem == "btrfs" and system_disks | length == 1
 
 - name: Mount the filesystem (btrfs)
   mount: src="{{ system_disks[0] }}{{ 'p2' if 'nvme' in system_disks[0] else '2' }}" path=/mnt state=mounted fstype=btrfs opts="compress-force=zstd,space_cache=v2"
   when: filesystem == "btrfs"
 
 - name: Touch LOCK file on mountpoint
@@ -63,7+63,7 @@
   command: gpg --locate-keys pierre@archlinux.de
   changed_when: false
 
-- name: Get signature verification output
+- name: Verify bootstrap image signature
   command: gpg --verify /tmp/archlinux-bootstrap-x86_64.tar.gz.sig
   changed_when: false