docs: networking: convert x25.txt to ReST

Not much to be done here:
- add SPDX header;
- add a document title;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index 7a4bdbc..75521e6 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -116,6 +116,7 @@
    vrf
    vxlan
    x25-iface
+   x25
 
 .. only::  subproject and html
 
diff --git a/Documentation/networking/x25.txt b/Documentation/networking/x25.rst
similarity index 96%
rename from Documentation/networking/x25.txt
rename to Documentation/networking/x25.rst
index c91c6d7..00e45d3 100644
--- a/Documentation/networking/x25.txt
+++ b/Documentation/networking/x25.rst
@@ -1,4 +1,8 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================
 Linux X.25 Project
+==================
 
 As my third year dissertation at University I have taken it upon myself to
 write an X.25 implementation for Linux. My aim is to provide a complete X.25