round_trace: fix documentation

my2to3/fixes/fix_round_trace.py

@@ -9,7 +9,7 @@ from my2to3.util import parse_type
 
 
 class FixRoundTrace(BaseDynamicTraceFix):
-  """Rewrites round(a[, b]) into round_traced(id, a[, b])
+  """Rewrites round(a[, b]) into round_traced(..., a[, b])
   """
   basename = "round"
   traced_information = "number", "ndigits"