Add CPI, LOCO and PermutationImportance to api.rst

[codecov[bot]]

Codecov Report

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

Project coverage is 76.35%. Comparing base (0299753) to head (b59dca0). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #22 +/- ## ======================================= Coverage 76.35% 76.35% ======================================= Files 46 46 Lines 2398 2398 ======================================= Hits 1831 1831 Misses 567 567 ```

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