docs: networking: fix x25-iface.rst heading & index order

Fix the chapter heading for "X.25 Device Driver Interface" so that it
does not contain a trailing '-' character, which makes Sphinx
omit this heading from the contents.

Reverse the order of the x25.rst and x25-iface.rst files in the index
so that the project introduction (x25.rst) comes first.

Fixes: 883780a ("docs: networking: convert x25-iface.txt to ReST")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Martin Schiller <ms@dev.tdt.de>
Cc: linux-x25@vger.kernel.org
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: rddunlap

Documentation/networking/index.rst

@@ -116,8 +116,8 @@ Contents:
    udplite
    vrf
    vxlan
-   x25-iface
    x25
+   x25-iface
    xfrm_device
    xfrm_proc
    xfrm_sync

Documentation/networking/x25-iface.rst

@@ -1,8 +1,7 @@
 .. SPDX-License-Identifier: GPL-2.0
 
-============================-
 X.25 Device Driver Interface
-============================-
+============================
 
 Version 1.1