mkfs: mark this wrapper as DEPRECATED

Theodore Ts'o:

 I'll add that I've never been convinced that the mkfs front end is all
 that useful.  It's probably better for people to explicitly run
 /sbin/mkfs.xfs, /sbin/mkfs.ext4, etc.., so you don't have to worry
 about which options get passed down to the file system specific mkfs
 program, and which ones are interpreted by /sbin/mkfs --- and I don't
 believe /sbin/mkfs adds enough (err, any?) value that using
 "/sbin/mkfs -t xxx" vs "/sbin/mkfs.xxx" makes any sense whatsoever.

... and I absolutely agree.

Reported-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Karel Zak <kzak@redhat.com>

Documentation/deprecated.txt

@@ -2,6 +2,9 @@ The following is a list of commands or features that are deprecated.  All
 deprecated utils are in maintenance mode and we keep them in source tree for
 backward compatibility only.
 
+What:   mkfs
+Why:    use filesystem specific mkfs.<type>.
+
 What:   fdisk -s <device>
 Why:    this does not belong to fdisk, use "blockdev --getsz"
 

disk-utils/mkfs.8

@@ -8,6 +8,8 @@ mkfs \- build a Linux filesystem
 .RB [ \-t
 .IR type "] [" fs-options ] " device " [ size ]
 .SH DESCRIPTION
+.B This mkfs frontend is deprecated in favour of filesystem specific mkfs.<type> utils.
+.PP
 .B mkfs
 is used to build a Linux filesystem on a device, usually
 a hard disk partition.  The