Update 12_day_regular_expressions.md

the first program snippet in quantifiers section output was "null" . the out put error at line no: 382

12_Day_Regular_expressions/12_day_regular_expressions.md

@@ -379,7 +379,7 @@ We can specify the length of the substring we look for in a text, using a curly
 const txt = 'This regular expression example was made in December 6,  2019.'
 const pattern = /\\b\w{4}\b/g  //  exactly four character words
 const matches = txt.match(pattern)
-console.log(matches)  //['This', 'made', '2019']
+console.log(matches)  //null
 ```
 
 ```js