Update CHANGES.

CHANGES.md

@@ -32,7 +32,7 @@ With the adoption of promises, D3 now uses the [Fetch API](https://fetch.spec.wh
 
 D3 no longer provides the d3.schemeCategory20* categorical color schemes. These twenty-color schemes were flawed because their grouped design could falsely imply relationships in the data: a shared hue can imply that the encoded data are part of a group (a super-category), while relative lightness can imply order. Instead, D3 now includes [d3-scale-chromatic](https://github.com/d3/d3-scale-chromatic), which implements excellent schemes from ColorBrewer, including [categorical](https://github.com/d3/d3-scale-chromatic/blob/master/README.md#categorical), [diverging](https://github.com/d3/d3-scale-chromatic/blob/master/README.md#diverging), [sequential single-hue](https://github.com/d3/d3-scale-chromatic/blob/master/README.md#sequential-single-hue) and [sequential multi-hue](https://github.com/d3/d3-scale-chromatic/blob/master/README.md#sequential-multi-hue) schemes. These schemes are available in both discrete and continuous variants.
 
-D3 now provides implementations of marching squares and density estimation via [d3-contour](https://github.com/d3/d3-contour)! There are two new [d3-selection](https://github.com/d3/d3-selection) methods: [*selection*.clone](https://github.com/d3/d3-selection/blob/master/README.md#selection_clone) for inserting clones of the selected nodes, and [d3.create](https://github.com/d3/d3-selection/blob/master/README.md#create) for creating detached elements. [Geographic projections](https://github.com/d3/d3-geo) now support [*projection*.angle](https://github.com/d3/d3-geo/blob/master/README.md#projection_angle), which has enabled several fantastic new [polyhedral projections](https://github.com/d3/d3-geo-polygon) by Philippe Rivière.
+D3 now provides implementations of [marching squares](https://beta.observablehq.com/@mbostock/d3-contour-plot) and [density estimation](https://beta.observablehq.com/@mbostock/d3-density-contours) via [d3-contour](https://github.com/d3/d3-contour)! There are two new [d3-selection](https://github.com/d3/d3-selection) methods: [*selection*.clone](https://github.com/d3/d3-selection/blob/master/README.md#selection_clone) for inserting clones of the selected nodes, and [d3.create](https://github.com/d3/d3-selection/blob/master/README.md#create) for creating detached elements. [Geographic projections](https://github.com/d3/d3-geo) now support [*projection*.angle](https://github.com/d3/d3-geo/blob/master/README.md#projection_angle), which has enabled several fantastic new [polyhedral projections](https://github.com/d3/d3-geo-polygon) by Philippe Rivière.
 
 Lastly, D3’s [package.json](https://github.com/d3/d3/blob/master/package.json) no longer pins exact versions of the dependent D3 modules. This fixes an issue with [duplicate installs](https://github.com/d3/d3/issues/3256) of D3 modules.