Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Observable Plot - Changelog
 
+## 0.2.4
+
+Released September 24, 2021.
+
+Update [Observable Hypertext Literal](https://github.com/observablehq/htl) to [0.3.1](https://github.com/observablehq/htl/releases/tag/v0.3.1).
+
 ## 0.2.3
 
 Released September 24, 2021.
@@ -8,6 +14,8 @@ Rect, bar, and rule marks now accept an *interval* option that allows you to der
 
 The new Plot.normalize and Plot.window methods return map methods for use in conjunction with Plot.map. This allows greater flexibility; for example, you can apply separate window methods to *y1* and *y2* to produce Bollinger bands.
 
+Update [D3](https://github.com/d3/d3) to [7.0.4](https://github.com/d3/d3/releases/tag/v7.0.4).
+
 ## 0.2.2
 
 Released September 19, 2021.