[css-text-3] text-transform has no effect on plain text copy/paste #627

Closes #627

Author: frivoal

css-text-3/Overview.bs

@@ -326,8 +326,10 @@ Characters and Letters</h3>
     </pre>
 
     <p>This property transforms text for styling purposes.
-      (It has no effect on the underlying content.)
-      Values have the following meanings:</p>
+    It has no effect on the underlying content,
+    and must not affect the content of a plain text copy &amp; paste operation.
+
+    <p>Values have the following meanings:
 
     <dl dfn-for=text-transform dfn-type=value>
       <dt><dfn>none</dfn></dt>