Update "New in doc" links

[adriendupuis]

Question	Answer
JIRA Ticket
Versions	All
Edition

Update "New in documentation" links for prior to 5.0 release

• All: Update links written during 4.6 era as there is risk they don't work now that latest is 5.0
  • REST API Ref: link to 4.6 REST API Ref (RAML) as the 5.0 REST API Ref (OpenAPI) as different anchors

Related: #2861 July 2025 mustn't be updated, just added on top of this one.

Checklist

• Text renders correctly
• Text has been checked with vale
• Description metadata is up to date
• Redirects cover removed/moved pages
• Code samples are working
• PHP code samples have been fixed with PHP CS fixer
• Added link to this PR in relevant JIRA ticket or code PR

[github-actions]

Preview of modified files

Preview of modified Markdown:

• docs/resources/new_in_doc.md

[mnocon]

Thank you!