Update README.

README.md

@@ -7,7 +7,7 @@ A [quadtree](https://en.wikipedia.org/wiki/Quadtree) recursively partitions two-
 
 ## Installing
 
-If you use NPM, `npm install d3-quadtree`. Otherwise, download the [latest release](https://github.com/d3/d3-quadtree/releases/latest). You can also load directly from [d3js.org](https://d3js.org), either as a [standalone library](https://d3js.org/d3-quadtree.v1.min.js) or as part of [D3 4.0](https://github.com/d3/d3). AMD, CommonJS, and vanilla environments are supported. In vanilla, a `d3` global is exported:
+If you use NPM, `npm install d3-quadtree`. Otherwise, download the [latest release](https://github.com/d3/d3-quadtree/releases/latest). You can also load directly from [d3js.org](https://d3js.org), either as a [standalone library](https://d3js.org/d3-quadtree.v1.min.js) or as part of [D3](https://github.com/d3/d3). AMD, CommonJS, and vanilla environments are supported. In vanilla, a `d3` global is exported:
 
 ```html
 <script src="https://d3js.org/d3-quadtree.v1.min.js"></script>
@@ -18,8 +18,6 @@ var quadtree = d3.quadtree();
 </script>
 ```
 
-[Try d3-quadtree in your browser.](https://tonicdev.com/npm/d3-quadtree)
-
 ## API Reference
 
 <a name="quadtree" href="#quadtree">#</a> d3.<b>quadtree</b>([<i>data</i>[, <i>x</i>, <i>y</i>]])