Update basics.md

docs/guide/basics.md

@@ -66,7 +66,7 @@ must start with an `@` symbol so that it can be differentiated from file/directo
 For example, the alias `@yii` refers to the Yii installation directory while `@web` contains the base URL for the currently running web application. Path aliases are supported in most places in the Yii core code. For example, `FileCache::cachePath` can accept both a path alias and a normal directory path.
 
 Path aliases are also closely related to class namespaces. It is recommended that a path
-alias be defined for each root namespace so that Yii's class autoloader can be used without
+alias should be defined for each root namespace so that Yii's class autoloader can be used without
 any further configuration. For example, because `@yii` refers to the Yii installation directory,
 a class like `yii\web\Request` can be autoloaded by Yii. If you use a third party library
 such as Zend Framework, you may define a path alias `@Zend` which refers to its installation