Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -80,6 +80,22 @@ function Likert(
 
 The new [_quantize_ scale type](./README.md#color-options) transforms a continuous domain into discrete, evenly-spaced thresholds. The _threshold_ scale type now supports descending domains.
 
+<img src="./img/quantize.png" width="640" alt="a scatterplot of Simpsons episodes showing the correlation between number of U.S. viewers and IMDb rating; the decline of the Simspons over time is shown with a quantized color encoding by season">
+
+```js
+Plot.plot({
+  grid: true,
+  color: {
+    type: "quantize",
+    legend: true
+  },
+  marks: [
+    Plot.ruleY([0]),
+    Plot.dot(simpsons, {x: "imdb_rating", y: "us_viewers_in_millions", fill: "season"})
+  ]
+})
+```
+
 The [bin transform](./README.md#bin) now coerces the input channel (the quantity being binned) to numbers as necessary. In addition, the bin transform now correctly handles typed array input channels representing temporal data. The [rect mark](./README.md#rect) now promotes the _x_ channel to _x1_ and _x2_ if the latter two are not specified, and likewise the _y_ channel to _y1_ and _y2_.
 
 Fix crash when **text** or **title** channels contain heterogenous types; each value is now independently formatted in a type-appropriate default formatter. Fix a rendering bug with one-dimensional rects whose opposite dimension is a band scale. Fix a rendering bug with swoopy arrows. Improve error messages to give more context.