docs: improve code comments (#1911)

src/lang/en.js

@@ -132,6 +132,9 @@ export default {
     cancel: 'Cancel',
     confirm: 'Confirm'
   },
+  example: {
+    warning: 'Creating and editing pages cannot be cached by keep-alive because keep-alive include does not currently support caching based on routes, so it is currently cached based on component name. If you want to achieve a similar caching effect, you can use a browser caching scheme such as localStorage. Or do not use keep-alive include to cache all pages directly. See details'
+  },
   errorLog: {
     tips: 'Please click the bug icon in the upper right corner',
     description: 'Now the management system are basically the form of the spa, it enhances the user experience, but it also increases the possibility of page problems, a small negligence may lead to the entire page deadlock. Fortunately Vue provides a way to catch handling exceptions, where you can handle errors or report exceptions.',

src/lang/es.js

@@ -132,6 +132,9 @@ export default {
     cancel: 'Cancelar',
     confirm: 'Confirmar'
   },
+  example: {
+    warning: 'Creating and editing pages cannot be cached by keep-alive because keep-alive include does not currently support caching based on routes, so it is currently cached based on component name. If you want to achieve a similar caching effect, you can use a browser caching scheme such as localStorage. Or do not use keep-alive include to cache all pages directly. See details'
+  },
   errorLog: {
     tips: 'Please click the bug icon in the upper right corner',
     description: 'Now the management system are basically the form of the spa, it enhances the user experience, but it also increases the possibility of page problems, a small negligence may lead to the entire page deadlock. Fortunately Vue provides a way to catch handling exceptions, where you can handle errors or report exceptions.',

src/lang/zh.js

@@ -132,6 +132,9 @@ export default {
     cancel: '取 消',
     confirm: '确 定'
   },
+  example: {
+    warning: '创建和编辑页面是不能被 keep-alive 缓存的，因为keep-alive 的 include 目前不支持根据路由来缓存，所以目前都是基于 component name 来进行缓存的。如果你想类似的实现缓存效果，可以使用 localStorage 等浏览器缓存方案。或者不要使用 keep-alive 的 include，直接缓存所有页面。详情见'
+  },
   errorLog: {
     tips: '请点击右上角bug小图标',
     description: '现在的管理后台基本都是spa的形式了，它增强了用户体验，但同时也会增加页面出问题的可能性，可能一个小小的疏忽就导致整个页面的死锁。好在 Vue 官网提供了一个方法来捕获处理异常，你可以在其中进行错误处理或者异常上报。',