docs: networking: convert lapb-module.txt to ReST

- add SPDX header;
- adjust title markup;
- mark code blocks and literals as such;
- mark tables as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/index.rst

@@ -75,6 +75,7 @@ Contents:
    ipvs-sysctl
    kcm
    l2tp
+   lapb-module
 
 .. only::  subproject and html
 

MAINTAINERS

@@ -9515,7 +9515,7 @@ F:	drivers/soc/lantiq
 LAPB module
 L:	linux-x25@vger.kernel.org
 S:	Orphan
-F:	Documentation/networking/lapb-module.txt
+F:	Documentation/networking/lapb-module.rst
 F:	include/*/lapb.h
 F:	net/lapb/
 

net/lapb/Kconfig

@@ -15,7 +15,7 @@ config LAPB
 	  currently supports LAPB only over Ethernet connections. If you want
 	  to use LAPB connections over Ethernet, say Y here and to "LAPB over
 	  Ethernet driver" below. Read
-	  <file:Documentation/networking/lapb-module.txt> for technical
+	  <file:Documentation/networking/lapb-module.rst> for technical
 	  details.
 
 	  To compile this driver as a module, choose M here: the