net: Fix a documentation bug wrt. ip_unprivileged_port_start

It cannot overlap with the local port range - ie. with autobind selectable
ports - and not with reserved ports.

Indeed 'ip_local_reserved_ports' isn't even a range, it's a (by default
empty) set.

Fixes: 4548b683b7 ("Introduce a sysctl that modifies the value of PROT_SOCK.")
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

@@ -904,8 +904,9 @@ ip_local_port_range - 2 INTEGERS
 	Defines the local port range that is used by TCP and UDP to
 	choose the local port. The first number is the first, the
 	second the last local port number.
-	If possible, it is better these numbers have different parity.
-	(one even and one odd values)
+	If possible, it is better these numbers have different parity
+	(one even and one odd value).
+	Must be greater than or equal to ip_unprivileged_port_start.
 	The default values are 32768 and 60999 respectively.
 
 ip_local_reserved_ports - list of comma separated ranges
@@ -943,8 +944,8 @@ ip_unprivileged_port_start - INTEGER
 	This is a per-namespace sysctl.  It defines the first
 	unprivileged port in the network namespace.  Privileged ports
 	require root or CAP_NET_BIND_SERVICE in order to bind to them.
-	To disable all privileged ports, set this to 0.  It may not
-	overlap with the ip_local_reserved_ports range.
+	To disable all privileged ports, set this to 0.  They must not
+	overlap with the ip_local_port_range.
 
 	Default: 1024