[doc] run playbooks in two separate commands
Unfortunatelly, `rbac-playbook` doesn't accept more than one playbook
at the time, so we need to run upgrade and provision playbooks in two
separate commands. I've submitted an issue
https://bitbucket.org/tflink/ansible_utils/issues/4/
requesting `rbac-playbook` to optionally accpet more playbooks.
Once the feature is available on batcave01, we can revert this
commit.