DOC: Update readme for rank mismatch

[HaoZeke]

As noted. The actual error is:

grasp/src/lib/lib9290/iniest2.f90:82:23:

   79 |          CALL DCOPY (NS, VEC(NS*(J-1)+1), 1, BASIS(NCF*(J-1)+1), 1)
      |                         2
......
   82 |       CALL DCOPY (NIV, EIGVAL, 1, BASIS(NIV*NCF+1), 1)
      |                       1
Error: Rank mismatch between actual argument at (1) and actual argument at (2) (scalar and rank-1)

[Babalion]

I would like to vote this up.