Update the snippet description (odd or even number)

snippets/even-or-odd-number.md

@@ -1,6 +1,6 @@
 ### Even or odd number
 
-Checks whether number is odd or even using the modulo (`%`) operator.
+Checks whether a number is odd or even using the modulo (`%`) operator.
 Returns `true` if the number is even, `false` if the number is odd.
 
 ```js