Explicitly note in the EXAMPLES section that uname(3) contains more details

MFC after:	1 week

usr.bin/uname/uname.1

@@ -28,7 +28,7 @@
 .\"	@(#)uname.1	8.3 (Berkeley) 4/8/94
 .\" $FreeBSD$
 .\"
-.Dd August 10, 2020
+.Dd Novermber 13, 2020
 .Dt UNAME 1
 .Os
 .Sh NAME
@@ -119,6 +119,9 @@ utility (except for
 .Fl a )
 will allow the corresponding data to be set to the contents
 of the environment variable.
+See
+.Xr uname 3
+for more information.
 .Sh EXIT STATUS
 .Ex -std
 .Sh EXAMPLES