Fix typo in Working with Lists Tutorial (#852)

Author: mark-dropbear

packages/lit-dev-content/site/tutorials/content/working-with-lists/00.md

@@ -1,7 +1,7 @@
 This tutorial explores different ways of rendering lists of items in
 Lit!
 
-Lit makes it easy to render any list of items. It has built-it support for
+Lit makes it easy to render any list of items. It has built-in support for
 iterables: pass an array (or other iterable) to a child expression and Lit will
 render each item in the array. This, combined with Lit's ability to render
 nested templates, and JavaScript patterns for transforming lists of data into