[Ingest docs] Ingest Pipelines Best Practices

[kilfoyle]

Philipp Kahr from consulting and team are putting together a really nice Ingest Pipelines Best Practices document that would be a really excellent thing to add to the public ingest docs.

Here's a draft document (apologies for sharing a link with limited access). We're hoping to edit and then port this content into the public docs sometime in May/June.

[philippkahr]

This is now ready, I started a PR with it already. Happy to engage.