update examples and sphnix docs for the new api (#63)

colossalai/logging/__init__.py

@@ -6,5 +6,11 @@ __all__ = ['get_dist_logger', 'DistributedLogger']
 def get_dist_logger(name='root'):
     """Get logger instance based on name. The DistributedLogger will create singleton instances,
     which means that only one logger instance is created per name.
+
+    :param name: name of the logger, name must be unique
+    :type name: str
+
+    :return: a distributed logger instance
+    :rtype: :class:`colossalai.logging.DistributedLogger`
     """
     return DistributedLogger.get_instance(name=name)