The man page says:

On success, the new nice value is returned (but see NOTES below).

Since the commit 4131356cd ("man*/, man-pages.7: VERSIONS, STANDARDS,
HISTORY: Reorganize sections"), this information is in VERSIONS.

Fixes: 4131356cd ("man*/, man-pages.7: VERSIONS, STANDARDS, HISTORY: Reorganize sections")
Signed-off-by: Kir Kolyshkin <redacted>
---
 man/man2/nice.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man/man2/nice.2 b/man/man2/nice.2
index 20d8d8ec1..743286eae 100644
--- a/man/man2/nice.2
+++ b/man/man2/nice.2

@@ -51,7 +51,7 @@ .SH DESCRIPTION
 .BR getrlimit (2)
 for details.
 .SH RETURN VALUE
-On success, the new nice value is returned (but see NOTES below).
+On success, the new nice value is returned (but see VERSIONS below).
 On error, \-1 is returned, and
 .I errno
 is set to indicate the error.

-- 
2.45.2