Ingest pipeline best practices

[philippkahr]

based on the discussions here: #1052

this is my first PR against the docs, and I am building a couple of new pages. I think it makes sense to split it out. I am putting it into that part of the docs. https://www.elastic.co/docs/manage-data/ingest/transform-enrich/ingest-pipelines The tips and tricks are generic and not specific to just o11y, or security.

[philippkahr]

There are a couple of things I need help with.

• Can someone proof read it and give suggestion on the ease of understanding.
• Does the file order make sense in the way I put it? Should we do an additional subfolder?
• Can you read through it please and here and there I think we can add links to different docs, like when I say remove. processor, we should link to the remove processor probably?
• Not a 100% convincend that common mistakes is the correct heading

[kilfoyle]

Thanks a lot for opening this Philipp! I've added the "Team:Obs" label since under the new docs organization that's where the ingest content will land.