Update readme.md

Author: onlytailei

readme.md

@@ -7,7 +7,7 @@ This is the cpp implementation of the [PythonRobotics](https://github.com/Atsush
 - opencv 3.3
 - Eigen 3
 - [CppAD](https://www.coin-or.org/CppAD/Doc/install.htm) / [IPOPT](https://www.coin-or.org/Ipopt/documentation/node14.html) (*for MPC convex optimization*)
-- ~~ROS~~ (*To make the repo lightweight :). Yet, we may still need it for 3D visualization.*) 
+- ~~ROS~~ (*~~To make the repo lightweight :)~~. Yet, we may still need it for 3D visualization.*) 
 
 ## Build
      $ mkdir build