Central Logging in kolla-ansible

[bouabid amine]

- [X] This doc is inaccurate in this way: It is not specified what are the components of the external E*K stack ?
Specifically, what to put in place of the "*" Logstash or Fluentd?
Which one is preferred?

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Release: 13.1.0.dev201 on 2021-01-18 23:14:14
SHA: 6dc3fbd3bbcff3c20e4f400d4033b9b075025d48
Source: https://opendev.org/openstack/kolla-ansible/src/doc/source/reference/logging-and-monitoring/central-logging-guide.rst
URL: https://docs.openstack.org/kolla-ansible/latest/reference/logging-and-monitoring/central-logging-guide.html