Bug 1756507

Description of problem:

Octavia Documentation should contain warning about not setting OctaviaCaCertFile, OctaviaCaKeyFile, OctaviaClientCertFile to a read-only location in the container.

https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/networking_guide/sec-octavia

If the following is set in the deployment environment:

  OctaviaCaCertFile: "/etc/pki/ca-trust/extracted/octavia/ca_02.pem"
  OctaviaCaKeyFile: "/etc/pki/ca-trust/extracted/octavia/cakey02.pem"
  OctaviaClientCertFile: "/etc/pki/ca-trust/extracted/octavia/client.pem"

The octavia continers will fail to startup with the following error in the `docker logs` output:

docker logs octavia_api
[...]
ERROR:__main__:Unexpected error:
Traceback (most recent call last):
  File "/usr/local/bin/kolla_set_configs", line 411, in main
    execute_config_strategy(config)
  File "/usr/local/bin/kolla_set_configs", line 377, in execute_config_strategy
    copy_config(config)
  File "/usr/local/bin/kolla_set_configs", line 306, in copy_config
    config_file.copy()
  File "/usr/local/bin/kolla_set_configs", line 150, in copy
    self._merge_directories(source, dest)
  File "/usr/local/bin/kolla_set_configs", line 97, in _merge_directories
    os.path.join(dest, to_copy))
  File "/usr/local/bin/kolla_set_configs", line 97, in _merge_directories
    os.path.join(dest, to_copy))
  File "/usr/local/bin/kolla_set_configs", line 97, in _merge_directories
    os.path.join(dest, to_copy))
  File "/usr/local/bin/kolla_set_configs", line 92, in _merge_directories
    self._set_properties(source, dest)
  File "/usr/local/bin/kolla_set_configs", line 117, in _set_properties
    self._set_properties_from_file(source, dest)
  File "/usr/local/bin/kolla_set_configs", line 122, in _set_properties_from_file
    shutil.copystat(source, dest)
  File "/usr/lib64/python2.7/shutil.py", line 98, in copystat
    os.utime(dst, (st.st_atime, st.st_mtime))
OSError: [Errno 30] Read-only file system: '/etc/pki/ca-trust/extracted'