Add LeetCode into coding practiсe section

ismagilov · web-flow · commit ac864b6bd169 · 2017-09-22T18:06:03.000+07:00
diff --git a/README.md b/README.md
@@ -166,3 +166,5 @@ But knowing the stuff will help you become better! :muscle:*
 - :link: [Exercism](http://www.exercism.io/)
 - :link: [CodeFights](https://codefights.com/)
 - :link: [Project Euler](https://projecteuler.net/)
+- :link: [LeetCode](https://leetcode.com/)
+
