List all tutorials contained on each of the main doxygen pages of the gz libraries in the main tutorials page

[j-rivero]

To gain more visibility on all the tutorials available and facilitate the work of the search engines and searchers of documentation in general, would be great to have the list of tutorials displayed by the doxygen main pages of each libraries (i.e: https://gazebosim.org/api/math/7/tutorials.html) inside the main documentation pages in the webpage (i.e: https://gazebosim.org/docs/garden/tutorials).

[j-rivero]

FYI: @nkoenig . I can not assign issue to people in this repo.