doc: release-notes-4.3: Mention the backlog support for listen()

Add a note that the backlog parameter of the listen() function is now
respected and the backlog support has been implemented for the TCP
server.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

doc/releases/release-notes-4.3.rst

@@ -170,6 +170,13 @@ New APIs and options
 
     * :kconfig:option:`CONFIG_HAWKBIT_REBOOT_NONE`
 
+* Networking
+
+  * Sockets
+
+    * :c:func:`zsock_listen` now implements the ``backlog`` parameter support. The TCP server
+      socket will limit the number of pending incoming connections to that value.
+
 * Power management
 
    * :c:func:`pm_device_driver_deinit`