[css-text-4] Add math-auto value

See w3c#5386

Author: frivoal

css-text-4/Overview.bs

@@ -564,7 +564,7 @@ Case Transforms: the 'text-transform' property</h3>
 
 	<pre class="propdef">
 	Name: text-transform
-	Value: none | [capitalize | uppercase | lowercase ] || full-width || full-size-kana
+	Value: none | [capitalize | uppercase | lowercase ] || full-width || full-size-kana || math-auto
 	Initial: none
 	Applies to: text
 	Inherited: yes
@@ -789,6 +789,10 @@ Case Transforms: the 'text-transform' property</h3>
 			text-transform/text-transform-full-size-kana-007.html
 			text-transform/text-transform-full-size-kana-008.html
 			</wpt>
+
+		<dt><dfn>math-auto</dfn>
+		<dd>
+			See [[mathml-core#new-text-transform-values]].
 	</dl>
 
 	<div class="example">