Is it possible to alter prefix for automated numbered figure/table captions for use in supplementary information documents? [FR]

[megaraptor1]

I have been using rmarkdown and bookdown to create supplementary information documents for my research using the method described here.

However, there does not appear to be an option to alter the heading used for figure and table captions in rmarkdown. In many cases the journals I submit to want their supplementary documents to be prefixed with an S. I.e., "Figure S1" and "Table S1" rather than Figure 1 or Table 1. I looked through options for rmarkdown and bookdown and it looks like the system for numbering figures and tables is baked into the command and cannot easily be altered. Quite a few journals seem to conform to this style, and I have gotten complaints when I refer to supplementary figures in the knitted rmarkdown document without an S in front of them. Is there any way to add this option to bookdown to conform to these journals' requirements?