Update README.md

add terminal markdown.

README.md

@@ -4,17 +4,18 @@ This project contains gazebo simulations environment for use with ros2.
 
 How use it:
 
-`
-create a ros2 workspace with this repo:
+```bash
+#create a ros2 workspace with this repo:
 mkdir -p ~/colcon_ws/src
 cd colcon_ws/src
 git clone https://gitlab.isae-supaero.fr/p.chauvin/isae_simulations_package.git
 cd ..
 colcon build
-`
+```
 
-`
+```bash
+#source gazebo env and workspace env before launch:
 . /usr/share/gazebo/setup.bash
 . install/setup.bash
 ros2 launch isae_simulations_package load_isae_world_into_gazebo.launch.py
-`
+```