Update handbook navigation structure and meta.json files

- Updated handbook/_meta.json to properly organize navigation
- Fixed duplicate entries by removing files that belong in subfolders
- Updated why folder title to 'Why does Jan exist?'
- Cleaned up why/_meta.json with proper titles for Open Superintelligence and Open-Source sections

docs/src/pages/handbook/_meta.json

@@ -1,5 +1,4 @@
 {
   "index": "Overview",
-  "open-superintelligence": "Open Superintelligence",
-  "betting-on-open-source": "Betting on Open-Source"
+  "why": "Why does Jan exist?"
 }

docs/src/pages/handbook/index.mdx

@@ -18,16 +18,6 @@ Jan's Handbook is a [living document](https://en.wikipedia.org/wiki/Living_docum
 
 ## Why does Jan exist?
 
-### [Open Superintelligence](/handbook/open-superintelligence)
-Building superintelligence that belongs to everyone, not just a few tech giants. We believe the future of AI should be open, accessible, and owned by the people who use it.
-
-### [Betting on Open-Source](/handbook/betting-on-open-source)
+- [Open Superintelligence](/handbook/open-superintelligence) - Building superintelligence that belongs to everyone, not just a few tech giants. We believe the future of AI should be open, accessible, and owned by the people who use it.
+- [Betting on Open-Source](/handbook/betting-on-open-source)
 Why we're betting on open-source as the future of AI and technology. Open-source has consistently won in the long term, and AI will be no different.
-
----
-
-## Quick Links
-
-- **For the curious**: Start with [Open Superintelligence](/handbook/open-superintelligence)
-- **For developers**: Learn about [Betting on Open-Source](/handbook/betting-on-open-source)
-- **For contributors**: Check out our [GitHub](https://github.com/menloresearch/jan) and [Discord](https://discord.gg/FTk2MvZwJH)

docs/src/pages/handbook/why/_meta.json

@@ -0,0 +1,4 @@
+{
+  "open-superintelligence": "Why Jan exists",
+  "betting-on-open-source": "Why we're betting on open-source"
+}

docs/src/pages/handbook/why/betting-on-open-source.mdx

@@ -1,5 +1,5 @@
 ---
-title: "Why Open-Source"
+title: "Why Jan is betting on Open-Source"
 description: "Why we're betting on open-source."
 ---