I'm being a bit lazy here but I haven't managed to find an answer in the documentation I've found so far, so I'm straight out asking for help 
I want to make a styler-type add-in that puts each sentence on a new line within the text sections of an RMarkdown file, probably by doing a find and replace on ". " ... you get the picture. But it wouldn't be a good idea to apply that find and replace to R code!
The styler documentation suggests that it can work with .Rmd files, but equally it says it only styles R source code, not the markdown text.
Is there a way of setting the scope of an add-in like the one I want to make, so it only operates outside of R code chunks?