Add Additional Custom Launch Button

[nilsleh]

We would like to add an additional launch button for our lightning-uq-box library which is a framework for Uncertainty Quantification for Deep Learning models which naturally often require GPU resources. The out-of-the-box support for google colab is nice, however, recently another framework called lightning studios emerged and we would like to add a launch button to our tutorials. In torchgeo we wrote a custom button to be added to notebooks, however, torchgeo is not under sphinx-book-theme documentation. I have tried a couple of things but no success so far, so was wondering whether you could give me any pointers about how to approach this? Thanks in advance.