Updated documentation

README.md

@@ -95,6 +95,12 @@ If the landmarks are loaded from the xodr file, *load_landmarks_from_xodr* param
 - ~**odom_fxyth** (Double; default: 0.05; min: 0.01; max: 1.0) Odom xyth sigma factor. 
 - ~**odom_sigma_min** (Double; default: 0.000001; min: 0.0000001; max: 1.0) Odom sigma min value. 
 
+### Rviz visualization markers
+
+This node publishes two different visualization markers:
+- Landmarks: Rectangular parallelepiped that represents each landmark position and orientation. The cyan ones are detected at current time.
+- Frame_data: This is a visualization of the SLAM problem. Red arrows are the poses of the robot at each frame. Cyan lines are the connection between the robot pose and the landmarks detected at the same frame.
+
 ## Installation
 
 [Download](http://ceres-solver.org/installation.html#getting-the-source-code) the latest stable Ceres release and install it following the [linux installation tutorial](http://ceres-solver.org/installation.html#linux).