Fix the command cited in the devref devstack doc to copy
samples/local.conf up one directory for use as basis for
a local.conf with manila plugin added.
TrivialFix
Change-Id: Iab4d35d41444a05757a3f2a5552e7b4939007327
Adds instructions on how to set up a fully functional manila
development environment using Devstack to the Developers Reference.
Partially-implements bp improve-manila-developer-docs
Change-Id: Id9781046716af2e04a0aea2734fbe4590bfd28dc