docs: networking: convert atm.txt to ReST

There isn't much to be done here. Just:

- add SPDX header;
- add a document title.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index 3e0a4bb23ef9..841f3c3905d5 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -41,6 +41,7 @@ Contents:
    altera_tse
    arcnet-hardware
    arcnet
+   atm
 
 .. only::  subproject and html