Remove ambiguity in kinematics.rst

[uavster]

The current phrasing ("it specifies that a collision check between the two bodies is either not required or wanted") is ambiguous.

Description

I guess the intended meaning was "the collision check is not required or the collision is wanted". I removed the "wanted" part to keep the wording consistent with the next sentence and remove the apparent redundancy.

Checklist

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[sjahr]

Good catch! What do you think about being even more specific about that? I think not required suggests that it might be an optional check but my understanding is that there won't be a check at all

[uavster]

Good catch! What do you think about being even more specific about that? I think not required suggests that it might be an optional check but my understanding is that there won't be a check at all

Much clearer. Thank you!