Snippet format update

To match the starter (for the migration)

snippets/toDecimalMark.md

@@ -1,11 +1,14 @@
-### toDecimalMark
+---
+title: toDecimalMark
+tags: utility,math,beginner
+---
 
 Use `toLocaleString()` to convert a float-point arithmetic to the [Decimal mark](https://en.wikipedia.org/wiki/Decimal_mark) form. It makes a comma separated string from a number.
 
- ```js
+```js
 const toDecimalMark = num => num.toLocaleString('en-US');
 ```
 
 ```js
 toDecimalMark(12305030388.9087); // "12,305,030,388.909"
-```
+```