Improve example playbooks

[neonmei]

Hello team! Current example playbooks could use a review/refresh and little README to make it easier to newcomers to the project. Also, it has been noted that some of them may be incorrect or outdated (for example wazuh-opendistro.yml or wazuh-agent.yml).

This issue is to keep track of those updates.

Regards.

[juresaht2]

wazuh-production-ready.yml first step with generate-certs seems to be plain wrong.

It seems to assume that only the certs will be generated, but instead the first indexer is deployed as well, which fails because it cannot connect to the cluster and so it hangs on the Initialize the Opensearch security index in Wazuh indexer task.

I don't know if this is something that used to behave differently with an older version of Ansible, but it doesn't work at all right now.