docs: bump disk prereq to 200GB
docs: bump disk prereq to 200GB

zcoinrocks/bitcore-node,kleetus/bitcore-node,snogcel/bitcore-node-dash,braydonf/bitcore-node,kleetus/bitcore-node,snogcel/bitcore-node-dash,zcoinrocks/bitcore-node,braydonf/bitcore-node