[css-fonts-4] Copy/paste error in font-stretch's computed style

w3c#1671

Author: litherum

css-fonts-4/Overview.bs

@@ -460,7 +460,7 @@ Initial: normal
 Applies to: all elements
 Inherited: yes
 Percentages: Not resolved.
-Computed value: numeric weight value (see description)
+Computed value: As specified
 Media: visual
 Animatable: As <<number>>
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