修复 gif demo 错误

docs/assets/example/gif.js

@@ -11,7 +11,7 @@ var art = new Artplayer({
         {
             name: 'gif',
             position: 'right',
-            html: '创建GIF',
+            html: 'Create GIF',
             mounted: $gif => {
                 art.plugins.artplayerPluginGif.attach($gif);
             },
@@ -22,7 +22,7 @@ var art = new Artplayer({
         {
             name: 'open',
             position: 'right',
-            html: '本地视频',
+            html: 'Local video',
             mounted: $open => {
                 art.plugins.localPreview.attach($open);
             },

docs/assets/example/playlist.js

@@ -8,7 +8,7 @@ var art = new Artplayer({
         {
             name: 'playlist',
             position: 'right',
-            html: '播放列表',
+            html: 'Playlist',
             click: () => {
                 art.plugins.artplayerPluginPlaylist.show();
             },
@@ -19,7 +19,7 @@ var art = new Artplayer({
         {
             name: 'prev',
             position: 'right',
-            html: '上一个',
+            html: 'Prev',
             click: () => {
                 art.plugins.artplayerPluginPlaylist.prev();
             },
@@ -30,7 +30,7 @@ var art = new Artplayer({
         {
             name: 'next',
             position: 'right',
-            html: '下一个',
+            html: 'Next',
             click: () => {
                 art.plugins.artplayerPluginPlaylist.next();
             },