btrfs: information for the information gods

Signed-off-by: Vincent Batts <vbatts@redhat.com>

ping @crosbymichael @jfrazelle @unclejack 
"btrfs-progs" is the upstream name of the project  https://btrfs.wiki.kernel.org/index.php/Main_Page#News , and this is what many/most distros packaged it as. Ubuntu calls it "btrfs-tools" though