Point navbar Reflex Framework link to /open-source (#6400)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Kastier1

packages/reflex-site-shared/src/reflex_site_shared/views/marketing_navbar.py

@@ -237,7 +237,7 @@ def platform_content() -> rx.Component:
                     "framework_pixel.svg",
                     "Reflex Framework",
                     "Iterate on full-stack apps in pure Python. No JavaScript required.",
-                    "/docs/getting-started/introduction/",
+                    "/open-source/",
                 ),
                 platform_item(
                     "cloud_pixel.svg",