Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -20,7 +20,7 @@ Plot.boxX(morley, {x: "Speed", y: "Expt"}).plot({x: {grid: true, inset: 6}})
 Plot.barY(d3.range(20).map(Math.random)).plot()
 ```
 
-The mark [sort options](./README.md#sort-options) now support implicit “width” and “height” channels, defined as |*x2* - *x1*| and |*y2* - *y1*| respectively. These channels are useful for sorting rects and bars by length. The *reverse* option defaults to true when sorting by these channels. When sorting by *y*, but not *y* channel is available, sorting will now fallback to sorting by *y2* if available; the same fallback logic applies to *x* and *x2*. (This behavior was previously supported on marks that support implicit stacking, but now applies universally to all marks.)
+The mark [sort options](./README.md#sort-options) now support implicit “width” and “height” channels, defined as |*x2* - *x1*| and |*y2* - *y1*| respectively. These channels are useful for sorting rects and bars by length. The *reverse* option defaults to true when sorting by these channels. When sorting by *y* and no *y* channel is available, sorting will now fallback to *y2* if available; the same fallback logic applies to *x* and *x2*. (This behavior was previously supported on marks that support implicit stacking, but now applies universally to all marks.)
 
 <img src="./img/sort-length.png" width="640" alt="a bar chart of energy production by source from 1949 to present, with categorical colors assigned in order of the tallest bar">