fix typo in logging.md

Author: dominikh

docs/logging.md

@@ -41,7 +41,7 @@ The level can be changed for single loggers or all loggers at once, by either us
 Example:
 
  bot = Cinch::Bot.new { }
- bot.loggers << Cinch::Loggers::FormattedLogger.new(File.open("/tmp/log.log", "a"))
+ bot.loggers << Cinch::Logger::FormattedLogger.new(File.open("/tmp/log.log", "a"))
  bot.loggers.level = :debug
  bot.loggers.first.level = :info