docs: make title more understandable (#2587)

add before to global guards title

Author: bbbbx

docs/guide/advanced/navigation-guards.md

@@ -4,7 +4,7 @@ As the name suggests, the navigation guards provided by `vue-router` are primari
 
 Remember that **params or query changes won't trigger enter/leave navigation guards**. You can either [watch the `$route` object](../essentials/dynamic-matching.md#reacting-to-params-changes) to react to those changes, or use the `beforeRouteUpdate` in-component guard.
 
-## Global Guards
+## Global Before Guards
 
 You can register global before guards using `router.beforeEach`:
 

docs/zh/guide/advanced/navigation-guards.md

@@ -8,7 +8,7 @@
 
 记住**参数或查询的改变并不会触发进入/离开的导航守卫**。你可以通过[观察 `$route` 对象](../essentials/dynamic-matching.md#响应路由参数的变化)来应对这些变化，或使用 `beforeRouteUpdate` 的组件内守卫。
 
-## 全局守卫
+## 全局前置守卫
 
 你可以使用 `router.beforeEach` 注册一个全局前置守卫：