SDF demo

[mohamedsayed18]

No description provided.

[maryaB-osr]

@mohamedsayed18 I left a partial review since there's quite a few comments. I'll let you address these first, and carry on the changes to the rest of the doc. I really like what you've done so far!

One thing I'd like to see is an outline of the sections - just the headings. something like:

# Title

## What is SDF?

## Breaking down the code

### The model

### Inertial properties

### Frames

## Conclusion

It's good to break a tutorial up into labeled sections as much as logically possible to help learners feel like they're progressing through a set of steps and not facing one huge task

[mohamedsayed18]

Thank you for your detailed feedback, waiting for the rest of the readme.
I'm working now on fixing these issues.

[chapulina]

I left a few suggestion on how to improve the vehicle SDF. The final vehicle I tested is here.

[chapulina]

Did another pass and left some more comments 👍

[chapulina]

I just have some minor comments.

I just had an idea so the user can see something happening by the end of this tutorial. What do you think of making the ground plane slightly rotated so that in the end of the tutorial, we can tell the user to press "play" and they see the car rolling downhill?

[chapulina]

I just have some final tweaks to suggest and then I think this is ready to go in.

As I mentioned on chat, I also think we should rename this tutorial from car_demo to some more descriptive name.