Fixing issue with getting tree

Tree previously returned the node collection array.  This contained all of the
nodes.  Returning just the root node is a more accurate representation of the
"tree" as it also contains all of the children.

Signed-off-by: Nate Brunette <n@tebru.net>
Replacing array syntax

Replaced instance of array with [].

Signed-off-by: Nate Brunette <n@tebru.net>
Updating readme

Adding spaces so it formats better on github.

Signed-off-by: Nate Brunette <n@tebru.net>