Create a figure to explain the parent_axis, child_axis, parent_pos, and child_pos vectors in Joint.

[moorepants]

The Joint class in mechanics has the ability to arbitrarily align and position the joint. For the non-trivial cases it is a bit difficult to understand. A figure is needed to help the user more clearly understand the relationship of the 4 vectors and the two connected bodies. I sketched this figure as a possible starting point:

Ideally, we create an SVG figure that can be modified and stored in the codebase.

@sidhu1012, fyi

[soma2000-lang]

@moorepants Can I work on this isssue?Please assign me this.

[moorepants]

Anyone can work on any issue. We don't assign people. Just open a "work in progress/draft" PR and link to this issue, then people will know you are working on it.