Address review comment

Author: odersky

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -44,7 +44,7 @@ class Compiler {
   /** Phases dealing with TASTY tree pickling and unpickling */
   protected def picklerPhases: List[List[Phase]] =
     List(new Pickler) ::            // Generate TASTY info
-    List(new Staging) ::            // Turn quoted trees into explicit run-time data structures
+    List(new Staging) ::            // Expand macros and turn quoted trees into explicit run-time data structures
     Nil
 
   /** Phases dealing with the transformation from pickled trees to backend trees */