update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -77,7 +77,7 @@ Diverging scales now support a *symmetric* option, which defaults to true, to en
 
 Diverging color scales now also support transformations via four new scale types: *diverging-sqrt*, *diverging-pow*, *diverging-log*, and *diverging-symlog*, corresponding to the *sqrt*, *pow*, *log*, and *symlog* quantitative scale types respectively. (The above choropleth uses a *diverging-log* scale to show relative change.)
 
-The new axis *line* option, which defaults to false, can be used to show a continuous line along the *x* or *y* axis to denote the extent. This is most useful when the opposite axis is ordinal and thus a rule cannot annotate a meaningful value such as zero; if the opposite axis is quantitative, a rule is generally preferred.
+The new axis *line* option, which defaults to false, can be used to show a continuous line along the *x* or *y* axis to denote the extent. This is most useful when the opposite axis is ordinal and thus a rule cannot annotate a meaningful value such as zero; if the opposite axis is quantitative, a rule is generally preferred. If set at the top level, applies to both *x* and *y*.
 
 <img width="640" alt="an empty plot showing a vertical line along the quantitative y-axis; the opposite x-axis is categorical" src="https://user-images.githubusercontent.com/230541/130247773-d868d261-9744-4d57-855a-61a2a870655b.png">
 
@@ -95,7 +95,7 @@ Plot.plot({
 })
 ```
 
-The *axis*, *label*, and *line* options (along with *grid*) can now be set as a top-level option, or a facet-level option, and inherited by *x* and *y* or *fx* and *fy*. This is most often useful for turning off all default axes or labels by setting the respective option to null.
+The *axis* and *label* options (along with *grid*) can now be set as a top-level option, or a facet-level option, and inherited by *x* and *y* or *fx* and *fy*. This is most often useful for turning off all default axes or labels by setting the respective option to null.
 
 ### Facets