Writer migration tasks

[bmorelli25]

On migration day (completed by migration team)

• Find and replace caution admonitions: Caution warning not rendered as caution warning #216
• UI text elements appear as bold and italic #316
  Find: \*\*\*(.*)\*\*\*
  Replace: **$1**
• Link with ^ doesn't work and adds values to the url #318
• Link checking for links relative to elastic.co #289
  Find: \]\(\/
  Replace: ](https://elastic.co/

After migration (writers)

• Add "applies to" frontmatter to files https://github.com/elastic/docs-projects/issues/262
• Lingering HTML elements #292
• Clean up Tables with cells that contain block elements #291
• more...

Post-freeze

• https://github.com/elastic/docs-projects/issues/389