Docs: remove link to non-exist how_to_use_a_different_vehicle.md

docs/howto/README.md

@@ -90,10 +90,9 @@
 - [How to install ubuntu](how_to_install_ubuntu.md)
 - [How to use IRC client on ubuntu](how_to_use_IRC_client_on_ubuntu.md)
 - [How to generate and push images into Docker](how_to_generate_and_push_docker_images.md)
-- [How to add a different vehicle](how_to_use_a_different_vehicle.md)
 
 ### Chinese versions
 
 - [How to generate and push images into Docker](how_to_generate_and_push_docker_images_cn.md)
 - [How to install ubuntu](how_to_install_ubuntu_cn.md)
-- [How to solve slow pull from cn](how_to_solve_slow_pull_from_cn.md)
\ No newline at end of file
+- [How to solve slow pull from cn](how_to_solve_slow_pull_from_cn.md)