[Doc] Post-migration doc restructuring (Logstash and Ingest)

[karenzone]

Partner PR: #16985

Consult and assist on post-migration doc restructuring, with focus on Logstash, Ingest, and Getting Started

• Shared (or referenced) content
  • Troubleshooting
  • Upgrade
  • Install
  • Release notes
• Deprecations
  • Deprecated integrations
  • See open issues
• Field refs
• Integration filter docs (multiple places) - edit, restructure, refine
  • Adding elastic_integration upgrade guidelines. #16979 (Comments)
  • A troubleshooting section added and more doc improvements. logstash-filter-elastic_integration#243
• https://github.com/elastic/ingest-dev/issues/4983
• Other...

Related

• Doc: Update release notes scripts to generate content in MD instead of ASCIIDOC #16853