Update README example to new MOI nonlinear interface

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (75ff19c) 84.66% compared to head (9740260) 84.66%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1059 +/- ## ======================================= Coverage 84.66% 84.66% ======================================= Files 44 44 Lines 3430 3430 ======================================= Hits 2904 2904 Misses 526 526 ```

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[pkofod]

Nice catch