Update changelog for 2.3.1 (#713)

* Prepare for 2.3.1 release.

Signed-off-by: Carlos Agüero <caguero@openrobotics.org>

Changelog.md

@@ -1,5 +1,19 @@
 ## VRX 2
 
+### VRX 2.3.1
+
+1. Fix simulation crash 
+    * [Pull Request 706](https://github.com/osrf/vrx/pull/706)
+
+1. Set IMU to reflect sensor position in global coordinates
+    * [Pull Request 708](https://github.com/osrf/vrx/pull/708)
+
+1. Updated code to use angle as input for wavefield parameter direction
+    * [Pull Request 708](https://github.com/osrf/vrx/pull/709)
+
+1. Create competition_mode argument
+    * [Pull Request 710](https://github.com/osrf/vrx/pull/710)
+
 ### VRX 2.3.0
 
 1. Enhancements to Perception Task 

README.md

@@ -20,7 +20,7 @@ The VRX environment is also the "virtual venue" for the [VRX Competition](https:
 
 ## Getting Started
 
- * Watch the [Release 1.5 Highlight Video](https://youtu.be/-2BP2P3CHYw) (Update for release 2.0 coming soon!)
+ * Watch the [Release 2.3 Highlight Video](https://vimeo.com/851696025).
  * The [VRX Wiki](https://github.com/osrf/vrx/wiki) provides documentation and tutorials.
  * The instructions assume a basic familiarity with the ROS environment and Gazebo.  If these tools are new to you, we recommend starting with the excellent [ROS Tutorials](http://wiki.ros.org/ROS/Tutorials)
  * For technical problems, please use the [project issue tracker](https://github.com/osrf/vrx/issues) to describe your problem or request support.