add arg-spec for new variable ssh_server_service_enabled

Signed-off-by: Sebastian Gumprich <rndmh3ro@users.noreply.github.com>

roles/ssh_hardening/meta/argument_specs.yml

@@ -259,6 +259,10 @@ argument_specs:
         default: true
         type: bool
         description: Set to `false` to disable the opensshd server.
+      ssh_server_service_enabled:
+        default: true
+        type: bool
+        description: Set to `false` to disable starting sshd at boot.
       ssh_server_hardening:
         default: true
         type: bool