Update README.md

Author: sunsided

README.md

@@ -1,17 +1,33 @@
 # RoboND Map My World
 
+This project is about performing SLAM using RGB-D based 
+Real-Time Appearance-Based Mapping via the RTAB-Map algorithm.
+It utilizes ROS' [`rtabmap`](http://wiki.ros.org/rtabmap) and
+[`rtabmap_ros`](http://wiki.ros.org/rtabmap_ros) packages and
+is developed against ROS Kinetic.
+
 ![](.readme/rgbd-sweep.webp)
 
-Building requires ROS Kinetic; you can try executing `./run_nvidia.sh` to drop into an X11 aware
-Docker container with NVIDIA GPU support.
+To build the project, you can try executing `./run_nvidia.sh` to drop
+into an X11 aware Docker container with NVIDIA GPU support.
 
-The following three pictures show the Gazebo environment, the graph generated by
-the [RTAB-Map](http://wiki.ros.org/rtabmap_ros) node, as well as the map generated by it.
+---
 
+The following three pictures show the simulation environment and SLAM results of
+the [RTAB-Map](http://wiki.ros.org/rtabmap_ros) node, as well as the map generated by it.
 For more information about RTAB-Map, see also the [offical website](http://introlab.github.io/rtabmap/).
 
+**The simulated environment:**
+
 ![The Gazebo environment](.readme/gazebo.jpg)
+
+**Nodes of the graph** generated by generated by RTAB-Map (after 
+111 rounds of global loop closure):
+
 ![The RTAB-Map graph](.readme/rtab-map.jpg)
+
+**The 2D map** generated by RTAB-Map:
+
 ![The RTAB-Map map](.readme/generated-map.jpg)
 
 ## Environment and Robot Control