Fix typo

It was not mentioned earlier in the article that “A property can be either an accessor (has get/set methods) or a data property (has a value), not both”

So，we should not say "once again".

Author: baooab

1-js/07-object-properties/02-property-accessors/article.md

@@ -134,7 +134,7 @@ alert(user.fullName); // John Smith
 for(let key in user) alert(key); // name, surname
 ```
 
-Please note once again that a property can be either an accessor (has `get/set` methods) or a data property (has a `value`), not both.
+Please note that a property can be either an accessor (has `get/set` methods) or a data property (has a `value`), not both.
 
 If we try to supply both `get` and `value` in the same descriptor, there will be an error: