go/types: be more precise in API comment

Change-Id: I24c4b08091bf3b8734f5dcdb9eac1a3582a4daa8
Reviewed-on: https://go-review.googlesource.com/135116Reviewed-by: Alan Donovan <adonovan@google.com>

src/go/types/api.go

@@ -180,7 +180,7 @@ type Info struct {
 	//
 	//     *ast.ImportSpec    *PkgName for imports without renames
 	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
-	//     *ast.Field         anonymous parameter *Var
+	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
 	//
 	Implicits map[ast.Node]Object