docs: networking: convert xfrm_sysctl.txt to ReST

Not much to be done here:

- add SPDX header;
- add a document title;
- add a chapter's markup;
- add to networking/index.rst.

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 ec83bd95e4e9..1630801cec19 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -120,6 +120,7 @@ Contents:
    xfrm_device
    xfrm_proc
    xfrm_sync
+   xfrm_sysctl
 
 .. only::  subproject and html