documentation: networking: devlink: fix prestera.rst formatting that causes build warnings

Fixes: 66826c43 ("documentation: networking: devlink: add prestera switched driver Documentation")
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-trap.rst

@@ -497,6 +497,7 @@ drivers:
 
   * :doc:`netdevsim`
   * :doc:`mlxsw`
+  * :doc:`prestera`
 
 .. _Generic-Packet-Trap-Groups:
 

Documentation/networking/devlink/index.rst

@@ -46,3 +46,4 @@ parameters, info versions, and other features it supports.
    qed
    ti-cpsw-switch
    am65-nuss-cpsw-switch
+   prestera

Documentation/networking/devlink/prestera.rst

 .. SPDX-License-Identifier: GPL-2.0
 
-=====================
+========================
 prestera devlink support
-=====================
+========================
 
 This document describes the devlink features implemented by the ``prestera``
 device driver.