[css-color-5][editorial] link defaults

Author: svgeesus

css-color-5/Overview.bs

@@ -36,6 +36,7 @@ spec:css-color-4; type:value; text:alpha-value
 spec:css-values-5; type:value; text:color
 spec:css-color-adjust-1; type:value; text:light
 spec:css-color-adjust-1; type:value; text:dark
+spec:css-color-4; type:value; text:rec2020
 </pre>
 <link rel="stylesheet" href="style.css" />
 <style>