refactor: rename 'Releases' to 'Documentatie'

Changed terminology from release notes to feature documentation
to better reflect the continuous build-in-public approach.

Changes:
- Navigation: "Releases" → "Documentatie"
- Page titles: "Release Notes" → "Feature Documentatie"
- Metadata descriptions updated
- Timeline link text updated
- Sidebar heading updated
- Template and example docs updated

The /releases route remains the same for stability,
but all user-facing text now says "Documentatie".

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/(marketing)/components/build-timeline.tsx

@@ -240,12 +240,12 @@ export const BuildTimeline = ({ data }: BuildTimelineProps) => {
                 </div>
               )}
 
-              {/* Link to detailed release notes */}
+              {/* Link to detailed documentation */}
               <a
                 href="/releases"
                 className="inline-flex items-center gap-2 text-teal-600 hover:text-teal-700 font-medium text-sm transition-colors"
               >
-                <span>Bekijk gedetailleerde release notes</span>
+                <span>Bekijk uitgebreide documentatie</span>
                 <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                   <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" />
                 </svg>