Update manual.markdown (home-assistant#13463)

SamyGarib · web-flow · commit 8383bfd6e21e · 2020-05-16T18:23:12.000+02:00
diff --git a/source/_integrations/manual.markdown b/source/_integrations/manual.markdown
@@ -135,7 +135,7 @@ In the configuration example below:
 alarm_control_panel:
   - platform: manual
     name: Home Alarm
-    code: 1234
+    code: '1234'
     pending_time: 30
     delay_time: 20
     trigger_time: 4
