Modify attribute for Ingest Guide

[karenzone]

The :ingest-guide: attribute is set to resolve to https://www.elastic.co/guide/en/fleet/{branch}. This PR updates the attribute.

Is the :ingest-guide: attribute currently in use anywhere? Docs-ci will tell us... but we might have to wait until after #2578 is merged.

UPDATE: Yes! The attribute is in use for some 7.x branches. See comments.

DO NOT MERGE until after #2578 has been merged.

[karenzone]

Some details and decisions to be addressed:

15:24:17 INFO:build_docs:Bad cross-document links:
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/elasticsearch/reference/7.9/docs-index_.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/elasticsearch/reference/7.9/index-templates.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/elasticsearch/reference/7.9/indices-put-template.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/elasticsearch/reference/7.9/set-up-a-data-stream.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/fleet/7.9/ingest-management-getting-started.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/elastic-agent-installation.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/fleet/7.9/run-elastic-agent.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/elastic-agent-installation.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/kibana/7.8/ingest-manager-settings-kb.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.8/index.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/kibana/7.8/ingest-manager.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.8/index.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/kibana/7.9/ingest-manager-settings-kb.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/index.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/kibana/7.9/ingest-manager.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/index.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/security/7.9/admin-page-ov.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-troubleshooting.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/security/7.9/advanced-settings.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/security/7.9/es-overview.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:  /tmp/docsbuild/target_repo/html/en/security/7.9/install-endpoint.html contains broken links to:
15:24:17 INFO:build_docs:   - en/ingest/7.9/elastic-agent-configuration.html
15:24:17 INFO:build_docs:   - en/ingest/7.9/ingest-management-overview.html
15:24:17 INFO:build_docs:   - en/ingest/7.9/unenroll-elastic-agent.html

[karenzone]

Looks like most of the offending references are for 7.8 and 7.9. If we fix those, then we should be able to repurpose the attribute without too much upheaval.

:ingest-guide:         https://www.elastic.co/guide/en/fleet/{branch}
:fleet-guide:          https://www.elastic.co/guide/en/fleet/{branch}

The :fleet-guide: attribute is set to resolve to the same entry, so this looks like an easy swap.

[karenzone]

@dedemorton, here's the PR where you made the original change.
Currently, both :ingest-guide: and :fleet-guide: resolve to https://www.elastic.co/guide/en/fleet/{branch}.

Now that our Ingest vision is becoming more clear, let's consider resetting :ingest-guide: to resolve to https://www.elastic.co/guide/en/ingest/{branch} to remove ambiguity. We'll have to clean up a few references in the 7.8/7.9 branches, but then we'd be clear to move forward.

Please let me know what you think. I don't want to plow ahead without input from you.

[dedemorton]

@karenzone I think that's a good idea. The original attribute was left over from when we were calling the UI ingest management rather than Fleet. :-) I'm starting to feel a bit of whiplash, TBH, but let's go with the change! Let me know how I can help.

[kilfoyle]

I'll get those broken links fixed up this week.

[kilfoyle]

@elasticmachine run elasticsearch-ci/docs rebuild

[dedemorton]

LGTM. PR just needs to be marked as ready for review :-)