Doc comments and error messages for "YiiRequirementChecker" have been adjusted.

yii/requirements/YiiRequirementChecker.php

@@ -66,7 +66,7 @@ class YiiRequirementChecker
 			$requirements = require($requirements);
 		}
 		if (!is_array($requirements)) {
-			$this->usageError("Requirements must be an array!");
+			$this->usageError('Requirements must be an array, "'.gettype($requirements).'" has been given!');
 		}
 		if (!isset($this->result) || !is_array($this->result)) {
 			$this->result = array(

yii/requirements/yiirequirements.php

@@ -1,6 +1,7 @@
 <?php
 /**
  * This is the Yii core requirements for the [[YiiRequirementChecker]] instance.
+ * These requirements are mandatory for any Yii application.
  */
 return array(
 	array(