sysctl.c: add text telling people to use CTL_UNNUMBERED

Hopefully this will help people to understand the new regime.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sysctl.c

@@ -203,7 +203,10 @@ static ctl_table root_table[] = {
 		.mode		= 0555,
 		.child		= dev_table,
 	},
-
+/*
+ * NOTE: do not add new entries to this table unless you have read
+ * Documentation/sysctl/ctl_unnumbered.txt
+ */
 	{ .ctl_name = 0 }
 };
 
@@ -992,6 +995,14 @@ static ctl_table vm_table[] = {
 		.extra1		= &zero,
 	},
 #endif
+/*
+ * NOTE: do not add new entries to this table unless you have read
+ * Documentation/sysctl/ctl_unnumbered.txt
+ */
+/*
+ * NOTE: do not add new entries to this table unless you have read
+ * Documentation/sysctl/ctl_unnumbered.txt
+ */
 	{ .ctl_name = 0 }
 };
 
@@ -1132,6 +1143,14 @@ static ctl_table fs_table[] = {
 		.child		= binfmt_misc_table,
 	},
 #endif
+/*
+ * NOTE: do not add new entries to this table unless you have read
+ * Documentation/sysctl/ctl_unnumbered.txt
+ */
+/*
+ * NOTE: do not add new entries to this table unless you have read
+ * Documentation/sysctl/ctl_unnumbered.txt
+ */
 	{ .ctl_name = 0 }
 };