[css-2020] Publication prep fixes w3c#4715 (comment)

Author: fantasai

css-2020/Overview.bs

@@ -19,6 +19,8 @@ Boilerplate: index no
 <pre class=link-defaults>
 spec:css-sizing-3; type:value; for:width; text:min-content
 spec:css-sizing-3; type:value; for:width; text:max-content
+spec:css-conditional-3; type:at-rule; text:@media
+spec:selectors-4; type:selector; text::lang()
 </pre>
 
 <div boilerplate=status>
@@ -629,7 +631,7 @@ Proprietary and Non-standardized Features</h4>
 <h4 id="de-facto">
 Market Pressure and De Facto Standards</h4>
 
-	If a feature is <a>unstable</a> (i.e. the spec has not stabilized yet), yet
+	If a feature is <a>unstable</a> (i.e. the spec has not yet stabilized), but
 
 	*	at least three UAs implement the feature
 		(<em>or</em> a UA has broken the other rules and shipped for broad use