A few minor fixes were noted in this review [1], and they
are addressed here.

TrivialFix

[1]: https://review.opendev.org/c/openstack/kolla-ansible/+/861392/

Change-Id: If30d9c2b48615dfb54edcb8d782c4c24b968ac4b

Kolla Ansible is switching to OpenSearch and is dropping support for
deploying ElasticSearch. This is because the final OSS release of
ElasticSearch has exceeded its end of life.

Monasca is affected because it uses both Logstash and ElasticSearch.
Whilst it may continue to work with OpenSearch, Logstash remains an
issue.

In the absence of any renewed interest in the project, we remove
support for deploying it. This helps to reduce the complexity
of log processing configuration in Kolla Ansible, freeing up
development time.

Change-Id: I6fc7842bcda18e417a3fd21c11e28979a470f1cf

Change-Id: I7d79a18599f54583ff4f38a554459fe02ada9ae7

Change-Id: I6d9ee98912120b9ece60ee22c7b0ad71dab8ed30

* Fix various typos and formatting.
* Add documentation about custom collector backend.
* Add documentation about custom storage backend.

Change-Id: If937afc5ce2a2747f464fbaf38a5dcf2e57ba04f
Closes-bug: #1940842