sysctl: remove obsolete comments

ctl_unnumbered.txt have been removed in Documentation directory so just
also remove this invalid comments

[akpm@linux-foundation.org: fix Documentation/sysctl/00-INDEX, per Dave]
Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/sysctl/00-INDEX

@@ -4,8 +4,6 @@ README
 	- general information about /proc/sys/ sysctl files.
 abi.txt
 	- documentation for /proc/sys/abi/*.
-ctl_unnumbered.txt
-	- explanation of why one should not add new binary sysctl numbers.
 fs.txt
 	- documentation for /proc/sys/fs/*.
 kernel.txt

kernel/sysctl.c

@@ -246,10 +246,6 @@ static struct 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
- */
 	{ }
 };
 
@@ -972,10 +968,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-/*
- * NOTE: do not add new entries to this table unless you have read
- * Documentation/sysctl/ctl_unnumbered.txt
- */
 	{ }
 };
 
@@ -1336,11 +1328,6 @@ static struct ctl_table vm_table[] = {
 		.extra2		= &one,
 	},
 #endif
-
-/*
- * NOTE: do not add new entries to this table unless you have read
- * Documentation/sysctl/ctl_unnumbered.txt
- */
 	{ }
 };
 
@@ -1496,10 +1483,6 @@ static struct ctl_table fs_table[] = {
 		.proc_handler	= &pipe_proc_fn,
 		.extra1		= &pipe_min_size,
 	},
-/*
- * NOTE: do not add new entries to this table unless you have read
- * Documentation/sysctl/ctl_unnumbered.txt
- */
 	{ }
 };