Update README.md (#165)

README.md

@@ -13,7 +13,7 @@ interested. There's also a discord server for discussions about Sapling and str
 general ([invite link](https://discord.gg/Amv3Tsb4fV)). OK enough from me, onto the real README!_
 
 Most of the ideas for this project come from my friend Shtanton's
-[blog post](http://shtanton.com/ex.html). The concept of directly editing syntax trees is called
+[blog post](http://shtanton.com/posts/ex.html). The concept of directly editing syntax trees is called
 ['structured editing'](https://en.wikipedia.org/wiki/Structure_editor) and is not new;
 the purpose of Sapling is to use ideas from structured editing to **speed up** moment-to-moment
 code editing, much how editors like Vim and Emacs speed up editing. Sapling's editing model will