zones: inject trailing new lines on Machine.WriteWireguardKeys()

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/zones/machine_rings.go

@@ -92,12 +92,12 @@ func (m *Machine) WriteWireguardKeys(ring int) error {
 		pub = ri.Keys.PrivateKey.Public().String()
 	}
 
-	err = m.WriteStringFile(key, "wg%v.key", ring)
+	err = m.WriteStringFile(key+"\n", "wg%v.key", ring)
 	if err != nil {
 		return err
 	}
 
-	err = m.WriteStringFile(pub, "wg%v.pub", ring)
+	err = m.WriteStringFile(pub+"\n", "wg%v.pub", ring)
 	if err != nil {
 		return err
 	}