Update 3.9.4.md

(cherry picked from commit 44ba27f)

Author: michaelklishin

release-notes/3.9.4.md

@@ -30,7 +30,7 @@ consistent release schedule.
 
    GitHub issue: [#3299](https://github.com/rabbitmq/rabbitmq-server/pull/3299)
 
- * Definitions now can be imported from different sources, including those provided by plugins. Local filesystem imports are still supported.
+ * Definitions now can be imported from different sources, including those provided by plugins. Original local filesystem source is still supported in a backwards-compatible way.
 
    The following `rabbitmq.conf` example uses a local file as the source: