Fix typo

Author: lex111

9-regular-expressions/21-regexp-unicode-properties/article.md

@@ -40,7 +40,7 @@ There are also other derived categories, like:
 For instance, let's look for a 6-digit hex number:
 
 ```js run
-let reg = /\p{Hex_Digit}{6}/u; // flag 'u' is requireds
+let reg = /\p{Hex_Digit}{6}/u; // flag 'u' is required
 
 alert("color: #123ABC".match(reg)); // 123ABC
 ```