Added link to binary packages doc to the documentation landing doc.
Added link to binary packages doc to the documentation landing doc.

Review: https://reviews.apache.org/r/71644/

kaysoky/mesos,dforsyth/mesos,Gilbert88/mesos,kaysoky/mesos,kaysoky/mesos,abudnik/mesos,abudnik/mesos,abudnik/mesos,dforsyth/mesos,abudnik/mesos,reneploetz/mesos,kaysoky/mesos,kaysoky/mesos,dforsyth/mesos,dforsyth/mesos,reneploetz/mesos,Gilbert88/mesos,dforsyth/mesos,Gilbert88/mesos,dforsyth/mesos,reneploetz/mesos,reneploetz/mesos,kaysoky/mesos,Gilbert88/mesos,reneploetz/mesos,reneploetz/mesos,kaysoky/mesos,abudnik/mesos,Gilbert88/mesos,Gilbert88/mesos,Gilbert88/mesos,reneploetz/mesos,abudnik/mesos,abudnik/mesos,dforsyth/mesos