Add a comment about ws_comma fixer

Author: edschofield

libfuturize/fixes/__init__.py

@@ -33,7 +33,7 @@
     'lib2to3.fixes.fix_throw',
     'lib2to3.fixes.fix_tuple_params',
     'lib2to3.fixes.fix_types',
-    'lib2to3.fixes.fix_ws_comma',
+    'lib2to3.fixes.fix_ws_comma',       # can perhaps decrease readability: see issue #58
     'lib2to3.fixes.fix_xreadlines',
 ])