Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -56,12 +56,18 @@ The *fill* and *stroke* mark options can now be expressed as patterns or gradien
 Plot.barY(alphabet, {x: "letter", y: "frequency", fill: "url(#gradient)"})
 ```
 
+The bin transform now supports the *interval* option, allowing numeric intervals such as integer binning with a nice default domain that aligns with interval boundaries. (The bin transform already supported time intervals as the *thresholds* option; time intervals can now also be specified as the *interval* option.) For example, if you want integer bins, say representing the hour of the day, use an *interval* of 1:
+
+<img src="./img/bin-interval.png" width="640" alt="a histogram of average traffic per hour of day">
+
+```js
+Plot.rectY(traffic, Plot.binX({y: "mean"}, {x: d => d.date.getUTCHours(), interval: 1, y: "value"}))
+```
+
 Plot now supports ARIA attributes for improved accessibility: aria-label, aria-description, aria-hidden. The top-level **ariaLabel** and **ariaDescription** options apply to the root SVG element. The new **ariaLabel** and **ariaDescription** scale options apply to axes; the label defaults to *e.g.* “y-axis” and the description defaults to the scale’s label (*e.g.*, “↑ temperature”). Marks define a group-level aria-label (*e.g.*, “dot”). There is also an optional **ariaLabel** channel for labeling data (*e.g.*, “E 12.7%”), and a group-level **ariaDescription** option for a human-readable description. The **ariaHidden** mark option allows the hiding of decorative elements from the accessibility tree.
 
 The new **paintOrder** mark option controls the [paint order](https://developer.mozilla.org/en-US/docs/Web/CSS/paint-order). The text mark’s paint order now defaults to *stroke*, with a stroke width of 3px and a stroke linejoin of *round*, making it easier to create a halo for separating labels from a busy background, improving legibility.
 
-The bin transform now supports the *interval* option, allowing numeric intervals such as integer binning with a nice default domain that aligns with interval boundaries. (The bin transform already supported time intervals as the *thresholds* option; time intervals can now also be specified as the *interval* option.)
-
 The returned scale object now exposes *bandwidth* and *step* values for *band* and *point* scales.
 
 Fix a crash in default tuple accessors for *x* and *y* when data is undefined. Fix a bug where “none” with surrounding whitespace or capital letters would not be recognized as a valid color. When a channel is specified as a boolean value (*e.g.*, `fill: true`), it is now considered a constant value rather than undefined. Fix a bug where an identity color legend would be rendered as the text “undefined” instead of showing nothing. If scale options are declared, but the scale has no defined type, domain, or data, a scale is no longer constructed rather than a default linear scale. The vector mark now respects the *frameAnchor* option. The default boolean color schemes have been adjusted slightly so that the false value is slightly darker, improving contrast against a white background.