Minor update in README of recent history exchange

Future is here: it is possible to disable plugins

(cherry picked from commit 2a3b96d)

Author: gomoripeti

deps/rabbitmq_recent_history_exchange/README.md

@@ -47,8 +47,7 @@ the message.
 
 ## Disabling the Plugin
 
-A future version of RabbitMQ will allow users to disable plugins. When
-you disable this plugin, it will delete all the cached messages.
+When you disable this plugin, it will delete all the cached messages.
 
 ## License