Add note about HTTPS being needed for device orientation.

doc/json-config-parameters.md

@@ -81,7 +81,8 @@ a link and visit this URL if Pannellum fails to work.
 
 If set to `true`, device orientation control will be used when the panorama is
 loaded, if the device supports it. If false, device orientation control needs
-to be activated by pressing a button. Defaults to `false`.
+to be activated by pressing a button. Defaults to `false`. Note that a secure
+HTTPS connection is required for device orientation access in most browsers.
 
 
 ### `showZoomCtrl` (boolean)