Update Logger format on docs, closes #6244

Author: josevalim

lib/logger/lib/logger.ex

@@ -205,7 +205,7 @@ defmodule Logger do
       `:level` configuration for the `:logger` application first.
 
     * `:format` - the format message used to print logs.
-      Defaults to: `"$time $metadata[$level] $levelpad$message\n"`.
+      Defaults to: `"\n$time $metadata[$level] $levelpad$message\n"`.
       It may also be a `{module, function}` tuple that is invoked
       with the log level, the message, the current timestamp and
       the metadata.