Merge pull request #37 from shapeblue/dynamic-roles-master

CLOUDSTACK-8562: add information on dynamic rolesAdds documentation on dynamic roles feature

/cc @swill @pdion891

* pr/37:
  CLOUDSTACK-8562: add information on dynamic roles

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>