docs: networking: convert sctp.txt to ReST

- add SPDX header;
- add a document title;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/index.rst

@@ -100,6 +100,7 @@ Contents:
    rds
    regulatory
    rxrpc
+   sctp
 
 .. only::  subproject and html
 

Documentation/networking/sctp.rst

@@ -1,35 +1,42 @@
-Linux Kernel SCTP 
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Linux Kernel SCTP
+=================
 
 This is the current BETA release of the Linux Kernel SCTP reference
-implementation.  
+implementation.
 
 SCTP (Stream Control Transmission Protocol) is a IP based, message oriented,
 reliable transport protocol, with congestion control, support for
 transparent multi-homing, and multiple ordered streams of messages.
 RFC2960 defines the core protocol.  The IETF SIGTRAN working group originally
-developed the SCTP protocol and later handed the protocol over to the 
-Transport Area (TSVWG) working group for the continued evolvement of SCTP as a 
-general purpose transport.  
+developed the SCTP protocol and later handed the protocol over to the
+Transport Area (TSVWG) working group for the continued evolvement of SCTP as a
+general purpose transport.
 
-See the IETF website (http://www.ietf.org) for further documents on SCTP. 
-See http://www.ietf.org/rfc/rfc2960.txt 
+See the IETF website (http://www.ietf.org) for further documents on SCTP.
+See http://www.ietf.org/rfc/rfc2960.txt
 
 The initial project goal is to create an Linux kernel reference implementation
-of SCTP that is RFC 2960 compliant and provides an programming interface 
-referred to as the  UDP-style API of the Sockets Extensions for SCTP, as 
-proposed in IETF Internet-Drafts.    
+of SCTP that is RFC 2960 compliant and provides an programming interface
+referred to as the  UDP-style API of the Sockets Extensions for SCTP, as
+proposed in IETF Internet-Drafts.
 
-Caveats:  
+Caveats
+=======
 
--lksctp can be built as statically or as a module.  However, be aware that 
-module removal of lksctp is not yet a safe activity.   
+- lksctp can be built as statically or as a module.  However, be aware that
+  module removal of lksctp is not yet a safe activity.
 
--There is tentative support for IPv6, but most work has gone towards 
-implementation and testing lksctp on IPv4.   
+- There is tentative support for IPv6, but most work has gone towards
+  implementation and testing lksctp on IPv4.
 
 
 For more information, please visit the lksctp project website:
+
    http://www.sf.net/projects/lksctp
 
 Or contact the lksctp developers through the mailing list:
+
    <linux-sctp@vger.kernel.org>

MAINTAINERS

@@ -14999,7 +14999,7 @@ M:	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
 L:	linux-sctp@vger.kernel.org
 S:	Maintained
 W:	http://lksctp.sourceforge.net
-F:	Documentation/networking/sctp.txt
+F:	Documentation/networking/sctp.rst
 F:	include/linux/sctp.h
 F:	include/net/sctp/
 F:	include/uapi/linux/sctp.h