are docs in guide/ folder out of date?

[giantwhale]

I don't see that ../tracker/rabit_demo.py file anywhere. Also I am wondering what's the expected output for the first c++ demo in guide.md, coz the output i got makes no sense to me at all.

$ python2.7 basic.py
@node[0] before-allreduce: a=[ 0. 1. 2.]
@node[0] after-allreduce-max: a=[ 0. 1. 2.]
@node[0] after-allreduce-sum: a=[ 0. 1. 2.]

[xydrolase]

See #27

[trivialfis]

Duplicated #27 .