[Visualization] obj instead of stl

[bd-bbeddard]

We use .obj files as part of our URDF model of Spot. This differs from the stl files currently indicated by the set up guide.

https://github.com/microsoft/spot-ros-wrapper#16-set-up-urdf-visualization-optional

[AustinDeric]

to my knowledge urdf's do not support .obj files. What visualization engines are you using?

.dae files are recommended for visualizations and .stl for collision geometry: http://wiki.ros.org/urdf/XML/link

I think the intent of this issue is satisfied with this PR: #17. I recommend merging and closing this issue.

[mklingen-bd]

Let me clarify. The documentation is incorrect -- we do not provide .stl models of the robot through the API. We provide .obj models. RVIZ supports any mesh format that assimp supports, which includes .obj. We do not provide collision models through the API.