Fix possibly goofy behaviour of intro-circ-creation ratelimiting
See commit e46d56a9b4458370cb8de0c92e10688402749845. The behaviour described by the old version of that comment is probably correct; the behaviour implemented by that chunk of code (and described in the new version of that comment) is daft.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information