Clarify changelog wording

Author: Wilfred

CHANGELOG.md

@@ -22,8 +22,9 @@ longer affect display.
 
 Improved descriptions of changes to binary files.
 
-Fixed an issue where difftastic would not use the full width of the
-terminal on side-by-side diffs when files had more than 1,000 lines.
+Fixed an issue (introduced after 0.65) where difftastic would not use
+the full width of the terminal on side-by-side diffs when files had
+more than 1,000 lines.
 
 ## 0.65 (released 23rd September 2025)