docs: improve code comments

Author: kenjis

user_guide_src/source/models/entities/009.php

@@ -8,14 +8,15 @@ class User extends Entity
 {
     protected $attributes = [
         'id'         => null,
-        'full_name'  => null, // In the $attributes, the key is the column name
+        'full_name'  => null, // In the $attributes, the key is the db column name
         'email'      => null,
         'password'   => null,
         'created_at' => null,
         'updated_at' => null,
     ];
 
     protected $datamap = [
+        // property_name => db_column_name
         'name' => 'full_name',
     ];
 }