Update/clean up btrfs help and man page V2

Update/clean up btrfs help and man page V2

Hi all,

enclose you can find a patch which improves the help of the btrfs commands,
 updates the INSTALL file  and  the btrfs (command) man page.

Regarding the help of the btrfs command:
- moved the "subvolume set-default" command in the "subvolume" commands group
- removed a wrong new line
- small tweak on the basis of Andreas suggestion

Regarding the btrfs command man page:
- renaming the command "device balance" in "filesystem balance" (thanks to
Andreas Phillipp to highlight that)
- adding the entry "subvolume find-new"
- document the switches of the command "filesystem defrag"
- document the <devid> facility of the command "filesystem resize"
- small tweak on the basis of Andreas suggestion

Regarding the INSTALL file, which was very old, I removed the reference of the
old btrfsctl utility and changed the examples using the btrfs command.
I removed the old (and now wrong) statement about the inability to delete a
subvolume/snapshot

Chris, you can pull the patch from the branch "help_cleanup" of the following
repository.

http://cassiopea.homelinux.net/git/btrfs-progs-unstable.git

(or you can browse the changes at
http://cassiopea.homelinux.net/git/btrfs-progs-unstable.git/?p=btrfs-
progs-unstable-all.git;a=summary)

The patch is very simple: only updates the man page, the INSTALL file and
 moves/updates some lines in the help of btrfs command. Comments are welcome.

Regards
G.Baroncelli

 INSTALL        |   29 ++++++++++++++++++++---------
 btrfs.c        |   24 ++++++++++++------------
 man/btrfs.8.in |   45 +++++++++++++++++++++++++--------------------
 3 files changed, 57 insertions(+), 41 deletions(-)

 all the block devices.
 .TP
@@ -138,21 +143,21 @@ can expand the partition before enlarging the filesystem
and shrink the
 partition after reducing the size of the filesystem.
 .TP

-\fBfilesystem show\fR [<uuid>|<label>]\fR
-Show the btrfs filesystem with some additional info. If no UUID or label is
-passed, \fBbtrfs\fR show info of all the btrfs filesystem.
+\fBfilesystem show\fR [<device>|<uuid>|<label>]\fR
+Show the btrfs filesystem with some additional info. If no argument is
+passed, \fBbtrfs\fR shows info of all the btrfs filesystems.
 .TP

-\fBdevice balance\fR \fI<path>\fR
+\fBfilesystem balance\fR \fI<path>\fR
 Balance the chunks of the filesystem identified by \fI<path>\fR
 across the devices.
 .TP

-\fBdevice add\fR\fI <dev> [<dev>..] <path>\fR
+\fBdevice add\fR\fI <device> [<device>...] <path>\fR
 Add device(s) to the filesystem identified by \fI<path>\fR.
 .TP

-\fBdevice delete\fR\fI <dev> [<dev>..] <path>\fR
+\fBdevice delete\fR\fI <device> [<device>...] <path>\fR
 Remove device(s) from a filesystem identified by \fI<path>\fR.
 .PP

Signed-off-by: Chris Mason <chris.mason@oracle.com>