Fix error related policy.json file
Fix error related policy.json file

Update manual-devstack guide by adding policy.json file.

Change-Id: I2996237cdb586629f3536ff6c54c9de0e220a623
Closes-Bug: #1477028

mjbrewer/testindex,openstack/magnum,ddepaoli3/magnum,ramielrowe/magnum,ArchiFleKs/magnum,ramielrowe/magnum,Tennyson53/SUR,annegentle/magnum,eshijia/SUR,annegentle/magnum,paulczar/magnum,ffantast/magnum,openstack/magnum,sajuptpm/magnum,ChengTiesheng/magnum,Tennyson53/magnum,Tennyson53/magnum,ChengTiesheng/magnum,dimtruck/magnum,ddepaoli3/magnum,paulczar/magnum,jay-lau/magnum,dimtruck/magnum,mjbrewer/testindex,ffantast/magnum,mjbrewer/testindex,Tennyson53/SUR,Alzon/SUR,ArchiFleKs/magnum,eshijia/magnum,sajuptpm/magnum,eshijia/SUR,Alzon/SUR,eshijia/magnum