Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -43,7 +43,7 @@ Plot.plot({
 })
 ```
 
-If an *r* channel is specified, the circles may have varying radius.
+If an *r* channel is specified, the circles may have varying radius. By default, the dodge transform sorts the input data by descending radius, such that the largest circles are placed first. The order of placement greatly affects the resulting layout; to change the placement order, use the standard mark **sort** option.
 
 [<img src="./img/dodge.png" width="640" alt="a chart showing the monthly percent change in travel by U.S. county in March 2020 after the coronavirus outbreak; each county is represented as a circle with area proportional to its population, positioned according to the change in travel; most counties, and especially those with stay-at-home orders, show a significant reduction in travel">](https://observablehq.com/@observablehq/plot-dodge)