fixed broken link

docs/guide/intro-upgrade-from-v1.md

@@ -19,7 +19,7 @@ Yii 2.0 fully embraces [Composer](https://getcomposer.org/), the de facto PHP pa
 of the core framework, as well as extensions, are handled through Composer. Please refer to
 the [Installing Yii](start-installation.md) section to learn how to install Yii 2.0. If you want to
 create new extensions, or turn your existing 1.1 extensions into 2.0-compatible extensions, please refer to
-the [Creating Extensions](extend-creating-extensions.md) section of the guide.
+the [Creating Extensions](structure-extensions.md#creating-extensions) section of the guide.
 
 
 PHP Requirements

docs/guide/start-installation.md

@@ -2,7 +2,7 @@ Installing Yii
 ==============
 
 You can install Yii in two ways, using [Composer](http://getcomposer.org/) or by downloading an archive file.
-The former is the preferred way, as it allows you to install new [extensions](extend-creating-extensions.md) or update Yii by simply running a single command.
+The former is the preferred way, as it allows you to install new [extensions](structure-extensions.md) or update Yii by simply running a single command.
 
 > Note: Unlike with Yii 1, standard installations of Yii 2 result in both, the framework and an application skeleton being downloaded and installed.