Combine 'Index mgmt' with 'Index mgmt in Kibana'

[kilfoyle]

As part of the ILM review it was pointed out that the very important Index management in Kibana page is kind of hard to find, since it's nested a few levels down in the "Index Lifecycle Management" section. It's also confusing that we have a few pages about managing indices.

This PR combines the contents of "Index management in Kibana" into Index Management (a section of the main, very prominent "Index basics" page at the top of the ToC).

Notes:

• For the removed Index management in Kibana page, I've changed the page to "hidden" in the ToC, replaced the content with a This page has moved note, and created a redirect in the redirect.yml file.
• The original pages differed in that one seemed mainly for Stack, one for both Serverless and Stack. In combining them I've used tabs to separate out the steps that differ.
• The "Index management in Kibana" page had a nice tutorial about setting up index templates. I've tested to make sure that it works on Serverless.
• We also have a Manage existing indices page. In a separate PR I've moved that to be nested under "Migrate to ILM" so it's clear that the page is not really about managing indices in general.
• I've updated outdated screencaps and also changed them to show the "Include hidden indices" option enabled, since this came up a few times in the ILM review.

See:

• Updated Index management
• Removed Index management in Kibana

Closes: #1569

[github-actions]

🔍 Preview links for changed docs

• deploy-manage/deploy/elastic-cloud/restrictions-known-problems.md
• explore-analyze/alerts-cases/watcher/watcher-ui.md
• manage-data/data-store/data-streams/logs-data-stream.md
• manage-data/data-store/index-basics.md
• manage-data/data-store/templates.md
• manage-data/ingest/transform-enrich/ingest-pipelines.md
• manage-data/ingest/transform-enrich/set-up-an-enrich-processor.md
• manage-data/lifecycle/index-lifecycle-management.md
• manage-data/lifecycle/index-lifecycle-management/index-management-in-kibana.md
• solutions/observability/apm/explore-data-in-elasticsearch.md

More links …

• solutions/observability/apm/reduce-storage.md
• solutions/observability/synthetics/manage-data-retention.md
• troubleshoot/observability/troubleshoot-mapping-issues.md

[eedugon]

I'll try to review this tomorrow. I'm totally ok with the initiative!

The majority of ILM docs were part of the elasticsearch guide and are felt like almost reference in some areas, or focused on API calls. So this is a great step forward.

[eedugon]

Great addings! I've added some suggestions with a bit more details in some areas that could feel confusing otherwise. Feel free to share your thoughts.

Also I'd like to share some extra thoughts for your consideration (maybe in future PRs):

1. Duplication:

With the proposed change we now have in the Templates section something that feels repetitive:

which feels similar to:

Maybe something to address as a separate issue (probably the entire "Templates + child" section needs extra love).

2. Narrative around index templates / templates / component templates:

In the Templates section we are trying to introduce a generic template concept explaining that templates can be of two different types (index templates and component templates). And we don't have them separated in different docs, neither with different headings / anchors for definition.

That makes linking to index-templates and component-templates a bit complicated, as we don't have a good section dedicated to component-templates and another dedicated to index-templates. Maybe something to address also in the future.

3. In relation with the previous, I think linking to the PUT component templates API doc to share a good description of what a component template is, is a prove that our "template" document needs love.

4. Something I haven't been able to touch because it wasn't part of the PR is:

Manage index templates [index-management-manage-index-templates]

An index template is a way to tell {{es}} how to configure an index when it is created.

I'd suggest something like:

An index template is a type of [template](/manage-data/data-store/templates.md) that tells {{es}} how to configure an index when it is created.

Similar to that, the component template introduction:

Manage component templates

Component templates are reusable building blocks that configure mappings, settings, and aliases.

For that I'd suggest something like:

Component templates are a type of [template](/manage-data/data-store/templates.md) used as reusable building blocks within index templates to configure index settings, mappings, and aliases.

With those suggestions I think the context of the link (templates.md) makes better sense, and it also implies to the reader that there are multiple types of templates (index / component).

[kilfoyle]

Thanks for the superb review @eedugon!

[florent-leborgne]

Experience docs changes LGTM 🥳