* add username customization for rabbitmq

* add changelog for rabbitmq

* Update builtin/logical/rabbitmq/path_config_connection.go
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>

* updating API docs

* moved to changelog folder
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>