Adding notes on libgazebo-dev

Author: ruffsl

gazebo/content.md

@@ -43,7 +43,11 @@ One thing to be careful about is that gzserver logs to files named `/root/.gazeb
 
 ### Devices
 
-As of Gazebo version 5.0, physics simulation under a headless instances of gzserver works fine. However some application may require image rendering camera views and ray traces for other sensor modalities. For Gazebo, this requires a running X server for rendering and capturing scenes. In addition, graphical hardware acceleration is also needed for reasonable realtime framerates. To this extent, mounting additional graphic devices into the container and linking to a running X server is required. In the interest of maintaining a general purpose and minimalistic image which is not tightly coupled to host system software and hardware, we do not include tags here with these additional requirements and instructions. You can however use this repo to build and customize your own images to fit your software/hardware configuration. The OSRF's Docker Hub organisation profile contains a Gazebo repo at [osrf/gazebo](https://registry.hub.docker.com/u/osrf/gazebo/) which is based on this repo but includes additional tags for these advanced use cases.
+As of Gazebo version 5.0, physics simulation under a headless instances of gzserver works fine. However some application may require image rendering camera views and ray traces for other sensor modalities. For Gazebo, this requires a running X server for rendering and capturing scenes. In addition, graphical hardware acceleration is also needed for reasonable realtime framerates. To this extent, mounting additional graphic devices into the container and linking to a running X server is required. In the interest of maintaining a general purpose and minimalistic image which is not tightly coupled to host system software and hardware, we do not include tags here with these additional requirements and instructions. You can however use this repo to build and customize your own images to fit your software/hardware configuration. The OSRF's Docker Hub organization profile contains a Gazebo repo at [osrf/gazebo](https://registry.hub.docker.com/u/osrf/gazebo/) which is based on this repo but includes additional tags for these advanced use cases.
+
+### Development
+
+If you not only wish to run Gazebo, but develope for it too, i.e. compile custom plug-ins or build upon messaging interfaces for ROS, this will require an installation of the dev package `libgazebo<version>-dev`. You can either build an image that does so, or again simply pull the relevant tagged image from OSRF's onbuild repo, [osrf/gazebo](https://registry.hub.docker.com/u/osrf/gazebo/).
 
 ## Deployment example
 
@@ -56,6 +60,7 @@ In this short example, we'll spin up a new container running gazebo server, conn
 > Now open a new bash session in the container using the same entrypoint to configure the environment. Then download the double_pendulum model and load it into the simulation.
 
 	docker exec -it gazebo bash
+	apt-get update && apt-get install curl
 	curl -o double_pendulum.sdf http://models.gazebosim.org/double_pendulum_with_base/model-1_4.sdf
 	gz model --model-name double_pendulum --spawn-file double_pendulum.sdf