Fix outdated solve() example in the kinematics module docstring

[gunyarakun]

The Usage example in the kinematics.py module docstring still showed the old solver API:

kin = Kinematics(setup, IKParams())
result = kin.solve(dt=0.1, n_iters=5)

Kinematics.solve() takes no arguments. The integration timestep and the iteration count are configured on IKParams instead, as dt and max_iters (not n_iters), and are read by _IKSolver at construction time. Copying the
example as written would raise a TypeError.

Updated to match the current API:

kin = Kinematics(setup, IKParams(dt=0.1, max_iters=5))
result = kin.solve()

Docstring only, no behavior change.

[lescidium]

LGTM!