Update css-fonts-4/Overview.bs

Co-authored-by: Chris Harrelson <chrishtr@gmail.com>

Author: xiaochengh

css-fonts-4/Overview.bs

@@ -2935,7 +2935,7 @@ Initial: normal
 
 The 'ascent-override', 'descent-override' and 'line-gap-override' descriptors define the
 <a spec="CSS-INLINE-3">ascent metric</a>, <a spec="CSS-INLINE-3">descent metric</a> and
-<a spec="CSS-INLINE-3">line gap metric</a> of the font.
+<a spec="CSS-INLINE-3">line gap metric</a> of the font, respectively.
 
 When the descriptor value is 'normal', the corresponding metric value is obtained from the
 font file directly.