btrfs-progs: make pretty Documentation/ build match the rest

btrfs-progs: make pretty Documentation/ build match the rest

This is the most important patch ever.  ;)

I found this to be less aesthetically pleasing than it was before:

     [CC]     btrfstune.o
 Making all in Documentation
     ASCIIDOC btrfs-convert.xml
     [LD]     btrfstune
     XMLTO btrfs-convert.8
     [CC]     btrfs-show-super.o
     GZIP btrfs-convert.8.gz
     [LD]     btrfs-show-super
     ASCIIDOC btrfs-debug-tree.xml
     XMLTO btrfs-debug-tree.8

so I shortened the pretty-text to match what we had before.

Also, make clean "quiet" like it is in the top dir.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
[Changed to ASCII and XMLTO]
Signed-off-by: David Sterba <dsterba@suse.cz>