Fix typos

snippets/palindrome.md

@@ -11,7 +11,7 @@ Checks if the given string is a palindrome.
 
 - Normalize the string to `String.prototype.toLowerCase()` and use `String.prototype.replace()` to remove non-alphanumeric characters from it.
 - Use the spread operator (`...`) to split the normalized string into individual characters.
-- Use `Array.prototype.reverse()`, `String.prototype.join()` and compare the result to the normalized string.
+- Use `Array.prototype.reverse()`, `Array.prototype.join()` and compare the result to the normalized string.
 
 ```js
 const palindrome = str => {