sleep: Fix man page about IGINFO output

Reviewed by:	des
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D58483

bin/sleep/sleep.1

@@ -29,7 +29,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 22, 2024
+.Dd July 27, 2026
 .Dt SLEEP 1
 .Os
 .Sh NAME
@@ -65,7 +65,7 @@ command receives a signal, it takes the standard action.
 When the
 .Dv SIGINFO
 signal is received, the estimate of the amount of seconds left to
-sleep is printed on the standard output.
+sleep is printed on the standard error output.
 .Sh IMPLEMENTATION NOTES
 The
 .Dv SIGALRM