fix: Remove overview from main navigation to restore JTBD flow (#3124)

Fixes navigation duplication where Introduction appeared both:
- As top-level Overview section
- Inside Discover section (via cross-reference)

Per JTBD methodology established in CLAUDE.md:
- Discover should be first (includes Introduction + Hosted Che content)
- Install should be second
- Removes duplication and follows proper user journey

Navigation flow now: Discover → Install → End User Guide → Administration → Extensions → Glossary

Co-authored-by: Claude Sonnet 4 <noreply@anthropic.com>

Author: gtrivedi88

antora.yml

@@ -5,7 +5,6 @@ version: next
 prerelease: true
 start_page: overview:introduction-to-eclipse-che.adoc
 nav:
-  - modules/overview/nav.adoc
   - modules/discover/nav.adoc
   - modules/install/nav.adoc
   - modules/end-user-guide/nav.adoc