Add render objects docs (#3192)

content/roadmaps/117-flutter/content/116-flutter-internals/100-render-objects.md

@@ -1 +1,6 @@
-# Render objects
+# Render Objects
+
+RenderObject's can be defined as "Objects" that render and manipulate layouts, sizes and draw the UI, providing the actual application rendering. They clean up some resources when dispose method is called, therefore it must be disposed by creator when is no longer used.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='blue' badgeText='Official Docs' href='https://api.flutter.dev/flutter/rendering/RenderObject-class.html'>RenderObject documentation</BadgeLink>