the WP_TESTS_DIR environment variable is now optional

CONTRIBUTING.md

@@ -16,29 +16,21 @@ If you want to add a new feature, please consider adding a new test for it as we
 
 The following instructions assume a UNIX-like environment (OS X, Linux, etc.).
 
-Step 1: Set un an environemt variable that defines the path to the test suite:
-
-```bash
-export WP_TESTS_DIR=/tmp/wordpress-tests/
-```
-
-This step will be needed each time you want to run the tests, so you might want to put it in your `.bashrc` file, to be executed automatically.
-
-Step 2: Install and configure the official WordPress testing suite:
+Step 1: Install and configure the official WordPress testing suite:
 
 ```bash
 ./bin/install-wp-tests
 ```
 
 Note that all data in the test DB will be _deleted_ once you run the tests.
 
-Step 4: Install PHPUnit via [Composer](https://getcomposer.org):
+Step 2: Install PHPUnit via [Composer](https://getcomposer.org):
 
 ```bash
 php composer.phar install --dev
 ```
 
-Step 5: Run the tests:
+Step 3: Run the tests:
 
 ```bash
 ./vendor/bin/phpunit