add changelog entry, update dead link in Docker build docs

changelog/13017.bugfix.md

@@ -0,0 +1 @@
+Flush messages when Kafka producer is closed. This is to ensure that all messages in the producer's internal queue are sent to the broker.

docs/docs/docker/building-in-docker.mdx

@@ -67,7 +67,7 @@ The initial project files should all be there, as well as a `models` directory t
 :::note
 If you run into permission errors, it may be because the `rasa/rasa` images
 run as user `1001` as a best practice, to avoid giving the container `root` permissions.
-Hence, all files created by these containers will be owned by user `1001`. See the [Docker documentation](https://docs.docker.com/edge/engine/reference/commandline/run/)
+Hence, all files created by these containers will be owned by user `1001`. See the [Docker documentation](https://docs.docker.com/reference/cli/docker/container/run/)
 if you want to run the containers as a different user.
 
 :::