Update mobile.html

docs/mobile.html

@@ -105,7 +105,7 @@
                     icon: '<img width="22" heigth="22" src="/assets/img/subtitle.svg">',
                     selector: [
                         {
-                            html: '显示字幕',
+                            html: '开关',
                             switch: true,
                             tooltip: '显示',
                             onSwitch: function (item) {