The man page says:

See NOTES for information on feature test macro requirements.

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/mmap.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man/man2/mmap.2 b/man/man2/mmap.2
index 12d60f500..a7a429137 100644
--- a/man/man2/mmap.2
+++ b/man/man2/mmap.2

@@ -34,7 +34,7 @@ .SH SYNOPSIS
 .BI "int munmap(void " addr [. length "], size_t " length );
 .fi
 .P
-See NOTES for information on feature test macro requirements.
+See VERSIONS for information on feature test macro requirements.
 .SH DESCRIPTION
 .BR mmap ()
 creates a new mapping in the virtual address space of

-- 
2.45.2