* [misc] add btn to go to old doc page.

module/doc/js/app.ui.js

@@ -239,3 +239,15 @@ window.setDocAppOptions = function(_, options)
     };
     return newOptions;
 };
+
+window.goToOldDocPage = function()
+{
+    const docApp = getDocApp();
+    if(!docApp) return;
+
+    zui.store.set('docAppEnabled', false);
+    const spaceType = docApp.signals.spaceType.value
+    const map = {mine: 'myspace', custom: 'teamspace', product: 'productspace', project: 'projectspace'};
+    const method = map[spaceType];
+    $.apps.openUrl($.createLink('doc', method));
+};

module/doc/ui/app.html.php

@@ -38,6 +38,15 @@ zui::docApp
     set::currentUser($this->app->user->account),
     set('$options', jsRaw('window.setDocAppOptions')),
 );
+
+btn
+(
+    setClass('absolute right-1.5 bottom-1.5 size-sm z-10'),
+    set::type('special-pale'),
+    set::icon('back'),
+    on::click()->call('goToOldDocPage'),
+    '切换回旧版界面',
+    css('#mainContent {position: relative}')
 );
 
 /* Modify navbar. 修改二级导航。 */