doc fixes [skip ci]

docs/guide/helper-url.md

@@ -69,13 +69,13 @@ to the above rules.
 Below are some examples of using this method:
 
 ```php
-// /index?r=site/index
+// /index.php?r=site/index
 echo Url::toRoute('site/index');
 
-// /index?r=site/index&src=ref1#name
+// /index.php?r=site/index&src=ref1#name
 echo Url::toRoute(['site/index', 'src' => 'ref1', '#' => 'name']);
 
-// /index?r=post/edit&id=100     assume the alias "@postEdit" is defined as "post/edit"
+// /index.php?r=post/edit&id=100     assume the alias "@postEdit" is defined as "post/edit"
 echo Url::toRoute(['@postEdit', 'id' => 100]);
 
 // http://www.example.com/index.php?r=site/index
@@ -105,13 +105,13 @@ will be replaced with the specified one.
 Below are some usage examples:
 
 ```php
-// /index?r=site/index
+// /index.php?r=site/index
 echo Url::to(['site/index']);
 
-// /index?r=site/index&src=ref1#name
+// /index.php?r=site/index&src=ref1#name
 echo Url::to(['site/index', 'src' => 'ref1', '#' => 'name']);
 
-// /index?r=post/edit&id=100     assume the alias "@postEdit" is defined as "post/edit"
+// /index.php?r=post/edit&id=100     assume the alias "@postEdit" is defined as "post/edit"
 echo Url::to(['@postEdit', 'id' => 100]);
 
 // the currently requested URL

docs/guide/runtime-routing.md

@@ -161,6 +161,10 @@ or an *absolute* route which will be normalized according to the following rules
 - If the route has no leading slash, it is considered to be a route relative to the current module and 
   will be prepended with the [[\yii\base\Module::uniqueId|uniqueId]] value of the current module.
 
+Starting from version 2.0.2, you may specify a route in terms of an [alias](concept-aliases.md). If this is the case,
+the alias will first be converted into the actual route which will then be turned into an absolute route according
+to the above rules.
+
 For example, assume the current module is `admin` and the current controller is `post`,
 
 ```php
@@ -177,6 +181,9 @@ echo Url::to(['post/index']);
 
 // an absolute route: /index.php?r=post/index
 echo Url::to(['/post/index']);
+
+// /index.php?r=post/index     assume the alias "@posts" is defined as "/post/index"
+echo Url::to(['@posts']);
 ```
 
 The [[yii\helpers\Url::to()]] method is implemented by calling the [[yii\web\UrlManager::createUrl()|createUrl()]] 

framework/helpers/BaseUrl.php

@@ -52,13 +52,16 @@ class BaseUrl
      * - If the route has no leading slash (e.g. `site/index`), it is considered to be a route relative
      *   to the current module and will be prepended with the module's [[\yii\base\Module::uniqueId|uniqueId]].
      *
+     * Starting from version 2.0.2, a route can also be specified as an alias. In this case, the alias
+     * will be converted into the actual route first before conducting the above transformation steps.
+     *
      * Below are some examples of using this method:
      *
      * ```php
-     * // /index?r=site/index
+     * // /index.php?r=site/index
      * echo Url::toRoute('site/index');
      *
-     * // /index?r=site/index&src=ref1#name
+     * // /index.php?r=site/index&src=ref1#name
      * echo Url::toRoute(['site/index', 'src' => 'ref1', '#' => 'name']);
      *
      * // http://www.example.com/index.php?r=site/index
@@ -66,6 +69,9 @@ class BaseUrl
      *
      * // https://www.example.com/index.php?r=site/index
      * echo Url::toRoute('site/index', 'https');
+     *
+     * // /index.php?r=post/index     assume the alias "@posts" is defined as "post/index"
+     * echo Url::toRoute('@posts');
      * ```
      *
      * @param string|array $route use a string to represent a route (e.g. `index`, `site/index`),
@@ -154,12 +160,15 @@ class BaseUrl
      * Below are some examples of using this method:
      *
      * ```php
-     * // /index?r=site/index
+     * // /index.php?r=site/index
      * echo Url::to(['site/index']);
      *
-     * // /index?r=site/index&src=ref1#name
+     * // /index.php?r=site/index&src=ref1#name
      * echo Url::to(['site/index', 'src' => 'ref1', '#' => 'name']);
      *
+     * // /index.php?r=post/index     assume the alias "@posts" is defined as "/post/index"
+     * echo Url::to(['@posts']);
+     *
      * // the currently requested URL
      * echo Url::to();
      *