uniq: exit status not documented enough

[Dan Jacobson]

The uniq man page does not mention an exit status. Bad.
The Info page says,
   An exit status of zero indicates success, and a nonzero value
   indicates failure.
Oh, well as
NAME
       uniq - remove duplicate lines from a sorted file
therefore if it fails to remove duplicate lines from a sorted file,
then it will return nonzero -- unless you clarify the exit status in
the docs.