Use ImageMagick instead of GraphicsMagick

docs/setup.en.md

@@ -53,7 +53,7 @@ Please install and setup these softwares:
 * *Node.js* and *npm*
 * **[MongoDB](https://www.mongodb.com/)**
 * **[Redis](https://redis.io/)**
-* **[GraphicsMagick](http://www.graphicsmagick.org/)**
+* **[ImageMagick](http://www.imagemagick.org/script/index.php)**
 
 ##### Optional
 * [Elasticsearch](https://www.elastic.co/) - used to provide searching feature instead of MongoDB

docs/setup.ja.md

@@ -54,7 +54,7 @@ web-push generate-vapid-keys
 * *Node.js* と *npm*
 * **[MongoDB](https://www.mongodb.com/)**
 * **[Redis](https://redis.io/)**
-* **[GraphicsMagick](http://www.graphicsmagick.org/)**
+* **[ImageMagick](http://www.imagemagick.org/script/index.php)**
 
 ##### オプション
 * [Elasticsearch](https://www.elastic.co/) - 検索機能を向上させるために用います。