Add comment based removal/addition for OSS

PiperOrigin-RevId: 187938803

Author: TedSander

lib/css/material/_material.scss

@@ -5,6 +5,11 @@
 @charset 'UTF-8';
 // Make sure the charset is set appropriately
 
+// acx:!g3-begin(internal comment)
+// Alphabet Core Experience Material Design styles, by the ACX team.
+// go/acx
+// acx:!g3-end
+
 // How to use me:
 //
 // This set of scss files should never output any css unless sass classes are