fix wrong quote format in doc/devstack.rst
fix wrong quote format in doc/devstack.rst

There should be an empty line after quote tag.

Change-Id: I34bd631b2e79c7bed3182a648234cda77948c287

leandroreox/gnocchi,idegtiarov/gnocchi-rep,leandroreox/gnocchi,sileht/gnocchi,sileht/gnocchi,idegtiarov/gnocchi-rep,gnocchixyz/gnocchi,gnocchixyz/gnocchi,idegtiarov/gnocchi-rep