Merge pull request markerikson#112 from josgraha/patch-1

Add Dan Abramov's React as a UI Runtime article

react-implementation.md

@@ -93,6 +93,10 @@
 
 #### Implementation and Internals
 
+- **React as a UI Runtime by Dan Abramov**  
+  https://overreacted.io/react-as-a-ui-runtime  
+  A deep dive into the React programming model from first principles
+
 - **React.js Reconciliation**  
   https://www.infoq.com/presentations/react-reconciliation  
   A video presentation digging into how React's reconciliation algorithm determines how to properly update nodes based on render output.
@@ -245,4 +249,4 @@
 
 - **What is React Fiber?**  
   https://giamir.com/what-is-react-fiber  
-  An overview of the React Fiber rewrite, and how React's reconciler has been rewritten to improve performance and make rendering more flexible.
+  An overview of the React Fiber rewrite, and how React's reconciler has been rewritten to improve performance and make rendering more flexible.