[enh] add rank-order information theory index

[knaaptime]

from reardon and bischoff (2011)

there's also more description in reardon (2011)

From the latter paper

using, e.g. the ACS data from 2021 (in SF), it's straightforward to cpmpute the pairwise measures

but im a little stuck on extrapolating the polynomial and averaging into a single measure