---
features:
  - Introduced option to send notifications from a background thread
    instead of blocking the service response to send the
    notification. This option is disabled by default, retaining
    previous behavior. Enable by setting ``nonblocking_notify`` to
    ``True`` in the middleware configuration. When enabled
    notifications will be queued for delivery in a single thread.
    Set ``send_queue_size`` to customize the length of this delivery
    queue (default size 1000).
  - Introduced option to customize the logging level using the
    ``log_level`` option (default WARNING).

Add release note for background thread notifier
Add release note for background thread notifier

Change-Id: Iad4e6c5e517ca6b01b0e2205be9fcd1cb302ec63
Related: I3da2b88b2bc9b7fd8c572a0085fa1d78c4f54701
Related: I9a8fad8036a0887653d2ad5f99f6b5b1b953c2db
