[css-fonts-4] fix w3c#4030 bad link

Author: svgeesus

css-fonts-4/Overview.bs

@@ -22,6 +22,7 @@ Ignored Terms: font-palette, <named-palette-color>
 spec:css-color-4; type:property; text:color
 spec:css-values; type:value; text:ex
 spec:css22; type:value; for:/; text:block
+spec:html; type:element; text:font
 </pre>