A recently merged CLI initalizer makes use of both string interpolation and macro expansion for the .short_help value. Interpolation may work but expansion definitely doesn't and thus the CLI documentation parser bails when it encounters this.

The patch in question was rushed into stable just prior to release and means that the 16.09 VPP release does not have wholly up to date documentation (it's missing only the additions of that patch). The patch has not yet made it to master but will cause problems there when it does.