docs: fix type of props option in RouteConfig api

Closes #2453

Author: posva

Diff for: docs/api/README.md

@@ -173,7 +173,7 @@ Since it's just a component, it works with `<transition>` and `<keep-alive>`. Wh
     name?: string; // for named routes
     components?: { [name: string]: Component }; // for named views
     redirect?: string | Location | Function;
-    props?: boolean | string | Function;
+    props?: boolean | Object | Function;
     alias?: string | Array<string>;
     children?: Array<RouteConfig>; // for nested routes
     beforeEnter?: (to: Route, from: Route, next: Function) => void;

Diff for: docs/ja/api/README.md

@@ -171,7 +171,7 @@ name ではないプロパティも描画されるコンポーネントに渡さ
     name?: string; // 名前付きルート用
     components?: { [name: string]: Component }; // 名前付き view 用
     redirect?: string | Location | Function;
-    props?: boolean | string | Function;
+    props?: boolean | Object | Function;
     alias?: string | Array<string>;
     children?: Array<RouteConfig>; // ネストされたルート用
     beforeEnter?: (to: Route, from: Route, next: Function) => void;

Diff for: docs/ru/api/README.md

@@ -173,7 +173,7 @@ sidebar: auto
     name?: string; // для именованных маршрутов
     components?: { [name: string]: Component }; // для именованных представлений
     redirect?: string | Location | Function;
-    props?: boolean | string | Function;
+    props?: boolean | Object | Function;
     alias?: string | Array<string>;
     children?: Array<RouteConfig>; // для вложенных маршрутов
     beforeEnter?: (to: Route, from: Route, next: Function) => void;

Diff for: docs/zh/api/README.md

@@ -177,7 +177,7 @@ sidebar: auto
     name?: string; // 命名路由
     components?: { [name: string]: Component }; // 命名视图组件
     redirect?: string | Location | Function;
-    props?: boolean | string | Function;
+    props?: boolean | Object | Function;
     alias?: string | Array<string>;
     children?: Array<RouteConfig>; // 嵌套路由
     beforeEnter?: (to: Route, from: Route, next: Function) => void;