Add ingest architecture docs to build

[karenzone]

No description provided.

[karenzone]

This PR gives us a way to generate previews of content that has been merged.
Merging is ON HOLD until we have sufficient content that we're comfortable surfacing on main page.

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

https://docs_2578.docs-preview.app.elstc.co/guide/en/ingest/current/intro-ingest-architectures.html

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[karenzone]

@elasticmachine run elasticsearch-ci/docs

[lcawl]

You might want to also add an alias in https://github.com/elastic/docs/blob/master/doc_build_aliases.sh, otherwise LGTM

[karenzone]

You might want to also add an alias in https://github.com/elastic/docs/blob/master/doc_build_aliases.sh

Thanks for the reminder. In this particular case, it's already there: #2546. :-)