fixed broken links

index.md

@@ -29,7 +29,7 @@ page_sections:
     url: https://github.com/forestryio/ubuild-jekyll
     button_text: 'See on GitHub '
   image:
-    image: "/uploads/2018/06/21/screenshot.jpg"
+    image: "/uploads/2019/07/30/screenshot.png"
     alt_text: Product Shot
   background_image: "/uploads/2018/06/21/hero-2-bg.png"
 - template: content-feature