Update polymer -> lit link to point at new lit repo instead of old li…

…t-element repo

README.md

@@ -4,7 +4,7 @@
 [![Published on npm](https://img.shields.io/npm/v/@polymer/polymer.svg)](https://www.npmjs.com/package/@polymer/polymer)
 [![Published on webcomponents.org](https://img.shields.io/badge/webcomponents.org-published-blue.svg)](https://www.webcomponents.org/element/@polymer/polymer)
 
-> ℹ️ Note: This is the current stable version of the Polymer library.  At Google I/O 2018 we announced a new Web Component base class, [`LitElement`](https://github.com/Polymer/lit-element), as a successor to the `PolymerElement` base class in this library.
+> ℹ️ Note: This is the current stable version of the Polymer library.  At Google I/O 2018 we announced a new Web Component base class, [`LitElement`](https://github.com/lit/lit), as a successor to the `PolymerElement` base class in this library.
 >
 > If you're starting a new project, we recommend that you consider using LitElement instead.
 >