Fix markdown linter

Author: ruffsl

ros/content.md

@@ -204,7 +204,7 @@ $ docker-compose rm
 
 ### ROS1 Bridge
 
-To ease ROS2 migration, [`ros1_bridge`](https://index.ros.org/p/ros1_bridge/github-ros2-ros1_bridge) is a ROS2 package that provides bidirectional communication between ROS1 and ROS2. As a minimal example, given the ROS2 Dockerfile above, we'll create the ROS1 equivalent below, and name the Dockerfile appropriately. 
+To ease ROS2 migration, [`ros1_bridge`](https://index.ros.org/p/ros1_bridge/github-ros2-ros1_bridge) is a ROS2 package that provides bidirectional communication between ROS1 and ROS2. As a minimal example, given the ROS2 Dockerfile above, we'll create the ROS1 equivalent below, and name the Dockerfile appropriately.
 
 ```dockerfile
 FROM ros:melodic
@@ -255,8 +255,8 @@ services:
 ## ROS2
 
 [Index](https://index.ros.org/doc/ros2/): ROS2 Documentation  
-[Design](https://design.ros2.org/): ROS2 Design Articles  
+[Design](https://design.ros2.org/): ROS2 Design Articles 
 
 ## ROS1
 
-[Wiki](http://wiki.ros.org/Documentation): ROS1 Documentation  
+[Wiki](http://wiki.ros.org/Documentation): ROS1 Documentation