Add note about smoke detector not working due to battery power

Issue #393

DEVICES.md

@@ -281,4 +281,4 @@ generic configurations known to work with multiple brands of device.
 - Qoto 03 smart water valve / sprinkler controller
 - SD123 HPR01 human presence radar
 - Universal remote control (supports sensors only)
-- VisorTech ZX-3150 smoke detector
+- VisorTech ZX-3150 smoke detector (likely not working locally, as this is battery powered)