Fix doc'n of FullPivLU re permutation matrices (bug 815). (transplanted from 64be8659f606970211ef83f12ebd401648c9685c)
Fix doc'n of FullPivLU re permutation matrices (bug 815).
(transplanted from 64be8659f606970211ef83f12ebd401648c9685c)

--HG--
branch : 3.2

robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen