[[!comment format=mdwn
 username="http://smcv.pseudorandom.co.uk/"
 nickname="smcv"
 subject="comment 2"
 date="2013-10-15T19:48:15Z"
 content="""
It should be as simple as putting the attachment's name in double square
brackets, like `\[[stuff.zip]]`? There isn't really any difference
between a download link and any other link.

(Or if it's attached to a different page, follow the same
[[ikiwiki/subpage/linkingrules]] as for pages, e.g. you might
write `\[[sandbox/stuff.zip]]` for a file attached to the [[sandbox]].)
"""]]