Set the ban reason in ban list as well (#82)

disco/api/client.py

@@ -376,6 +376,7 @@ class APIClient(LoggingClass):
     def guilds_bans_create(self, guild, user, delete_message_days=0, reason=None):
         self.http(Routes.GUILDS_BANS_CREATE, dict(guild=guild, user=user), params={
             'delete-message-days': delete_message_days,
+            'reason': reason,
         }, headers=_reason_header(reason))
 
     def guilds_bans_delete(self, guild, user, reason=None):