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]

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

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

[utf]

Thanks!