[css-text-4] Fix a typo

Author: xfq

css-text-4/Overview.bs

@@ -1450,7 +1450,7 @@ Text Spacing Character Classes</h4>
 			or is categorized as East Asian Fullwidth (F) by [[!UAX11]].
 			Also includes RIGHT SINGLE QUOTATION MARK (U+2019) and RIGHT DOUBLE QUOTATION MARK (U+201D).
 			May also include [=fullwidth colon punctuation=] and/or [=fullwidth dot punctuation=]
-			((<a href="#fullwidth-ambiguous">see below</a>).
+			(<a href="#fullwidth-ambiguous">see below</a>).
 			When trimmed, the right (for horizontal text) or bottom (for vertical text) half is kerned.
 
 		<dt><dfn>fullwidth middle dot punctuation</dfn>