Add Forms 13.5, 15.2 and 16 release notes

[ronaldbarendse]

📋 Description

Add Forms 13.5.0, 15.2.0, 16.0.0-rc4, 16.0.0-rc5 and 16.0.0 release notes.

📎 Related Issues (if applicable)

n/a

✅ Contributor Checklist

I've followed the Umbraco Documentation Style Guide and can confirm that:

• Code blocks are correctly formatted.
• Sentences are short and clear (preferably under 25 words).
• Passive voice and first-person language (“we”, “I”) are avoided.
• Relevant pages are linked.
• All links work and point to the correct resources.
• Screenshots or diagrams are included if useful.
• Any code examples or instructions have been tested.
• Typos, broken links, and broken images are fixed.

Product & Version (if relevant)

Forms 13.5.0
Forms 15.2.0
Forms 16.0.0-rc4
Forms 16.0.0-rc5
Forms 16.0.0

Deadline (if relevant)

🚀

📚 Helpful Resources

• 🧾 Umbraco Contribution Guidelines
• ✍️ Umbraco Documentation Style Guide

[eshanrnh]

The PR looks great, @ronaldbarendse 🙌