Guide for using SDK with Two Party App Sessions (#102)

Adds comprehensive documentation for multi-party application sessions,
helping developers understand how to create, manage, and close app
sessions with multiple participants using the Yellow Network and
Nitrolite protocol. Includes reference to full working demo script in
sdk-examples repo

<img width="1024" height="334" alt="Screenshot 2026-01-16 at 11 03
29 PM"
src="https://github.com/user-attachments/assets/00666ad7-ee6e-469e-9d56-e590eeafe37c"
/>

<img width="1825" height="1246" alt="Screenshot 2026-01-16 at 11 03
49 PM"
src="https://github.com/user-attachments/assets/c24fbd39-a9aa-4312-bd5f-f976edabc324"
/>

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Co-authored-by: Steven Zeiler <[email protected]>

Author: stevenzeiler

docs/guides/index.md

@@ -7,4 +7,7 @@ displayed_sidebar: guidesSidebar
 
 # Guides
 
-**[Migration Guide](/docs/guides/migration-guide)** - Guide for migrating from previous versions of the Yellow SDK.
+**[Migration Guide](/docs/guides/migration-guide)** - Guide for migrating from previous versions of the Yellow SDK.
+
+
+**[Multi-Party App Sessions](/docs/guides/multi-party-app-sessions)** - Learn how to create, manage, and close multi-party application sessions using the Yellow Network and Nitrolite protocol.