doc: Change the udp/sctp rmem/wmem default value.

The SK_MEM_QUANTUM was changed from PAGE_SIZE to 4096.
Signed-off-by: NTonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

@@ -755,13 +755,13 @@ udp_rmem_min - INTEGER
 	Minimal size of receive buffer used by UDP sockets in moderation.
 	Each UDP socket is able to use the size for receiving data, even if
 	total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
-	Default: 1 page
+	Default: 4K
 
 udp_wmem_min - INTEGER
 	Minimal size of send buffer used by UDP sockets in moderation.
 	Each UDP socket is able to use the size for sending data, even if
 	total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
-	Default: 1 page
+	Default: 4K
 
 CIPSOv4 Variables:
 
@@ -2101,7 +2101,7 @@ sctp_rmem - vector of 3 INTEGERs: min, default, max
 	It is guaranteed to each SCTP socket (but not association) even
 	under moderate memory pressure.
 
-	Default: 1 page
+	Default: 4K
 
 sctp_wmem  - vector of 3 INTEGERs: min, default, max
 	Currently this tunable has no effect.