No bequest tax in documentation

[rickecon]

OG-Core allows the specification of a linear tax rate on bequests received (estate tax, tau_bq). See default_parameters.json line 1058, tax.py lines 288, 460, 489, 493, 495, 497, and aggregates.py lines 355, 364, and 384. But this parameter is only described in the parameters API of the documentation (see parameters.md line 521 and parameters.py line 164) and not in the theory. We should include this in the theory documentation.

$$ (1 - \tau^{bq}) {bq}_{j,s,t} $$

cc: @jdebacker

[jdebacker]

Good find.

A question -- should the warm glow bequest motive value the before or after-tax bequest value? I'm not sure what seems more appropriate.