added Tools subcategory

Author: nirajpandkar

README.md

@@ -3,7 +3,9 @@
 
 [English](http://git.io/git-tips) | [中文](https://github.com/521xueweihan/git-tips)
 
-[git-tip](https://www.npmjs.com/package/git-tip) - A handy CLI to make optimum use of these tips.
+### Tools
+
+* [git-tip](https://www.npmjs.com/package/git-tip) - A handy CLI to make optimum use of these tips.
 
 P.S: All these commands are tested on `git version 2.7.4 (Apple Git-66)`.