Updated Codeception installation guide [skip ci]

docs/guide/test-environment-setup.md

@@ -1,8 +1,6 @@
 Testing environment setup
 ======================
 
-> Note: This section is under development.
-
 Yii 2 has officially maintained integration with [`Codeception`](https://github.com/Codeception/Codeception) testing
 framework that allows you to create the following test types:
 
@@ -14,36 +12,12 @@ Yii provides ready to use test sets for all three test types in both
 [`yii2-basic`](https://github.com/yiisoft/yii2-app-basic) and
 [`yii2-advanced`](https://github.com/yiisoft/yii2-app-advanced) project templates.
 
-In order to run tests you need to install [Codeception](https://github.com/Codeception/Codeception).
-You can install it either locally - for particular project only, or globally - for your development machine.
-
-For the local installation use following commands:
-
-```
-composer require "codeception/codeception=2.1.*"
-composer require "codeception/specify=*"
-composer require "codeception/verify=*"
-```
-
-For the global installation you will need to use `global` directive:
+Codeception comes preinstalled with both basic and advanced project templates.
+In case you are not using one of these templates, Codeception could be installed
+by issuing the following console commands:
 
 ```
-composer global require "codeception/codeception=2.1.*"
-composer global require "codeception/specify=*"
-composer global require "codeception/verify=*"
+composer require codeception/codeception
+composer require codeception/specify
+composer require codeception/verify
 ```
-
-If you've never used Composer for global packages before, run `composer global status`. It should output:
-
-```
-Changed current directory to <directory>
-```
-
-Then add `<directory>/vendor/bin` to you `PATH` environment variable. Now we're able to use `codecept` from command
-line globally.
-
-> Note: global installation allows you use Codeception for all projects you are working on your development machine and
-  allows running `codecept` shell command globally without specifying path. However, such approach may be inappropriate,
-  for example, if 2 different projects require different versions of Codeception installed.
-  For the simplicity all shell commands related to the tests running around this guide are written assuming Codeception
-  has been installed globally.