Add passive mode exchange declaration option to amqp consumer input (#3995)

plugins/inputs/amqp_consumer/README.md

@@ -19,6 +19,8 @@ The following defaults are known to work with RabbitMQ:
   url = "amqp://localhost:5672/influxdb"
   ## AMQP exchange
   exchange = "telegraf"
+  ## Exchange passive mode
+  exchange_passive = false
   ## AMQP queue name
   queue = "telegraf"
   ## Binding Key