feat: 优化每日环球展览 iMuseum title 字段 (#2279)

* fix: 修复路由参数默认值

* feat: 优化 title 字段

lib/router.js

@@ -469,7 +469,7 @@ router.get('/google/doodles/:language?', require('./routes/google/doodles'));
 router.get('/pigtails', require('./routes/pigtails'));
 
 // 每日环球展览 iMuseum
-router.get('/imuseum/:city/:type', require('./routes/imuseum'));
+router.get('/imuseum/:city/:type?', require('./routes/imuseum'));
 
 // AppStore
 router.get('/appstore/update/:country/:id', require('./routes/appstore/update'));