Fix comments

CHANGELOG.md

@@ -200,7 +200,7 @@
 - Role: mongo_3_0
   - Changed MONGO_STORAGE_ENGINE to default to wiredTiger which is the default in 3.2 and 3.4 and what edX suggests be used even on 3.0.
     If you have a mmapv1 3.0 install, override MONGO_STORAGE_ENGINE to be mmapv1 which was the old default.
-  - Ready for deploying Mongo 3.2  
+  - Support parsing the replset JSON in 3.2 and 3.0 
 
 - Role: xqueue
   - Added `EDXAPP_CELERY_BROKER_USE_SSL` to allow configuring celery to use TLS.

playbooks/library/mongodb_replica_set

@@ -269,8 +269,9 @@ def update_replset(rs_config):
         if not check_config_subset(rs_config, changed_rs_config):
             module.fail_json(msg="Failed to validate that the replica set was changed", new_config=changed_rs_config, config=rs_config)
 
-    #Remove settings from changed_rs_config before exit to avoid
-    #problem with exit_json() and unserializable ObjectId
+    # Remove settings from changed_rs_config before exit to avoid
+    # problem with exit_json() and unserializable ObjectId
+    # because MongoDB returns JSON which is not serializable
     if changed_rs_config.get('settings') is not None:
         changed_rs_config['settings'] = None