Add "Create Phone Number" kata

Author: juanantonioledesma

6-kyu/create-phone-number.md

@@ -0,0 +1,35 @@
+<h1>Create Phone Number <sup><sup>6 Kyu</sup></sup></h1>
+
+<sup>
+  <a href="https://www.codewars.com/kata/525f50e3b73515a6db000b83">
+    <strong>LINK TO THE KATA</strong>
+  </a> - <code>ARRAYS</code> <code>STRINGS</code> <code>REGULAR EXPRESSIONS</code> <code>ALGORITHMS</code>
+</sup>
+
+## Description
+
+Write a function that accepts an array of 10 integers (between 0 and 9), that returns a string of those numbers in the form of a phone number.
+
+**Example**
+
+```javascript
+createPhoneNumber([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) // => returns "(123) 456-7890"
+```
+
+The returned format must be correct in order to complete this challenge.
+
+Don't forget the space after the closing parentheses!
+
+## Solution
+
+```javascript
+const createPhoneNumber = numbers => {
+  const stringNumbers = numbers.join('')
+
+  const prefix = stringNumbers.substr(0, 3)
+  const firstGroup = stringNumbers.substr(3, 3)
+  const lastGroup = stringNumbers.substr(6, 4)
+
+  return `(${prefix}) ${firstGroup}-${lastGroup}`
+}
+```

README.md

@@ -31,6 +31,7 @@ JavaScript katas on Codewars are programming challenges that help you improve yo
 - **[Convert string to camel case](./6-kyu/convert-string-to-camel-case.md)**
 - **[Count the smiley faces!](./6-kyu/count-the-smiley-faces.md)**
 - **[Counting Duplicates](./6-kyu/counting-duplicates.md)**
+- **[Create Phone Number](./6-kyu/create-phone-number.md)**
 - **[Decode the Morse code](./6-kyu/decode-the-morse-code.md)**
 - **[Delete occurrences of an element if it occurs more than n times](./6-kyu/delete-occurrences-of-an-element-if-it-occurs-more-than-n-times.md)**
 - **[Detect Pangram](./6-kyu/detect-pangram.md)**