Add fibonacci example to tutorial

[JaGeo]

@utf , I simply added the example to the tutorial as well. This is more a result of me being unable to look beyond the documentation (and being to tired to think clearly), but maybe others also overlook the example folder.

[codecov[bot]]

Codecov Report

Merging #494 (03e7e2e) into main (08fbf5f) will not change coverage. Report is 4 commits behind head on main. The diff coverage is n/a.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #494 +/- ## ======================================= Coverage 99.86% 99.86% ======================================= Files 20 20 Lines 1509 1509 Branches 415 415 ======================================= Hits 1507 1507 Misses 2 2 ```

[utf]

Thanks!