added icon to detectfans button in kcm

package/contents/ui/KCM.qml

@@ -51,6 +51,7 @@ Item {
         Button {
             Layout.alignment: Qt.AlignCenter
             text: i18n("Detect fans")
+            iconName: "dialog-password"
             onClicked: kcm.loader.detectSensors()
         }
     }