I have recently been working with the Bioconductor core team to add markdown capacity to the support site and am glad to let you know that it will appear shortly. I know it had been a wish list item for a long time and I am really excited I had the opportunity to implement it. Just to be clear, it will be markdown and not rmarkdown, although they are similar. What's markdown? If you don't already know here are some good tutorials.
Hope you enjoy! Lucas