Use correct casing for MB

These values refer to Megabytes, not Megabits.

Fix #1295

Author: jeffwidman

kafka/consumer/fetcher.py

@@ -85,7 +85,7 @@ def __init__(self, client, subscriptions, metrics, **configs):
                 performs fetches to multiple brokers in parallel so memory
                 usage will depend on the number of brokers containing
                 partitions for the topic.
-                Supported Kafka version >= 0.10.1.0. Default: 52428800 (50 Mb).
+                Supported Kafka version >= 0.10.1.0. Default: 52428800 (50 MB).
             max_partition_fetch_bytes (int): The maximum amount of data
                 per-partition the server will return. The maximum total memory
                 used for a request = #partitions * max_partition_fetch_bytes.

kafka/consumer/group.py

@@ -74,7 +74,7 @@ class KafkaConsumer(six.Iterator):
             ensure that the consumer can make progress. NOTE: consumer performs
             fetches to multiple brokers in parallel so memory usage will depend
             on the number of brokers containing partitions for the topic.
-            Supported Kafka version >= 0.10.1.0. Default: 52428800 (50 Mb).
+            Supported Kafka version >= 0.10.1.0. Default: 52428800 (50 MB).
         max_partition_fetch_bytes (int): The maximum amount of data
             per-partition the server will return. The maximum total memory
             used for a request = #partitions * max_partition_fetch_bytes.