[css-ruby] Fix broken parenthetical in example

Author: frivoal

css-ruby-1/Overview.bs

@@ -109,7 +109,7 @@ What is ruby?</h3>
 		</div>
 
 		In Japanese typography, this case is sometimes called
-		taigo ruby (Japanese: <span lang="ja">対語ルビ</span>) or group-ruby (per-word ruby), (
+		taigo ruby (Japanese: <span lang="ja">対語ルビ</span>, i.e. per-word ruby) or group-ruby,
 		because the annotation as a whole is associated
 		with multi-character word (as a whole).
 	</div>