fix application path (laradock#1781)

* fix application path

In the "env.sample" , "APP_CODE_PATH_HOST"  was written. I fixed Documentation.

Author: tadaken3

DOCUMENTATION/content/getting-started/index.md

@@ -81,10 +81,10 @@ We'll need to do step 1 of the [Usage](#Usage) section now to make this happen.
 cp env-example .env
 ```
 
-At the top, change the `APPLICATION` variable to your project path.
+At the top, change the `APP_CODE_PATH_HOST` variable to your project path.
 
 ```
-APPLICATION=../project-z/
+APP_CODE_PATH_HOST=../project-z/
 ```
 
 Make sure to replace `project-z` with your project folder name.