Update CHANGES.

CHANGES.md

@@ -975,10 +975,10 @@ Likewise, in place of 3.x’s d3.time.weekOfYear, in 4.0 you would say:
 d3.timeWeek.count(d3.timeYear(now), now); // 24
 ```
 
-The new *interval*.count is of course more general. For example, you can use it to compute the week-of-month:
+The new *interval*.count is of course more general. For example, you can use it to compute hour-of-week for a weekly heatmap:
 
 ```js
-d3.timeWeek.count(d3.timeMonth(now), now); // 2
+d3.timeHour.count(d3.timeWeek(now), now); // 64
 ```
 
 Here are all the equivalences from 3.x to 4.0: