docs: add 'Integration and IO' rubric to api reference docs

[jakobchwastek]

fix issue #629

[codecov[bot]]

Codecov Report

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

Project coverage is 100.00%. Comparing base (9374ac9) to head (37d7771).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #630 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 55 55 Lines 2463 2463 Branches 621 621 ========================================= Hits 2463 2463 ```

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[jakobchwastek]