[css-text-4] Add test info

Author: frivoal

css-text-4/Overview.bs

@@ -10565,6 +10565,11 @@ CJK Punctuation Spacing: the 'text-spacing-trim' property</h3>
 		<dfn><<spacing-trim>></dfn> = space-all | normal | space-first | trim-start | trim-both | trim-all
 	</pre>
 
+	<wpt>
+		parsing/text-spacing-trim-invalid.html
+		parsing/text-spacing-trim-valid.html
+	</wpt>
+
 	<dl dfn-for=text-spacing-trim dfn-type=value>
 		<dt><dfn>space-all</dfn>
 		<dd>