Good idea. Here’s the list of file extensions for uploads right now. I’ll add .md too for later. Some of these won’t preview correctly in the Uploads page yet, but they will work when on your blog.
mp3
m4a
m4v
mov
mp4
png
gif
webp
svg
pdf
ttf
woff
woff2
eot
xml
txt
js
json
css
html