[Sane-analysis] Update to wiki section on pion asymmetries

[O. A. Rondon]

Luwani's thesis section on pion asymmetries led me to notice that there
was a typo on my wiki section on Perpendicular pion asymmetries, where
the fit result in the text was shown as
A_perp = A_{92.4} = 0.00122+/-0.00157
with the opposite sign as that shown on the plot.

The plot's sign is correct. Luwani also has it right as
A_perp = A_{92.4} = -0.00122+/-0.00157

The typo propagated to the calculation of
A_{90} = 0.0022+/-0.0016
which is wrong. The correct value is

A_{90} = [A_{92.4} - A_{0} cos 92.4]/sin 92.4 = -0.0003+/-0.0016

which is much more consistent with a zero perpendicular asymmetry than
the old value.

The updated wiki is at
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Fits_to_charged_pion_asymmetries#Perpendicular_Asymmetry

Cheers,

Oscar