docs: networking: convert dctcp.txt to ReST

- add SPDX header;
- adjust title markup;
- mark code blocks and literals as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/dctcp.txt Documentation/networking/dctcp.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
 DCTCP (DataCenter TCP)
-----------------------
+======================
 
 DCTCP is an enhancement to the TCP congestion control algorithm for data
 center networks and leverages Explicit Congestion Notification (ECN) in
 the data center network to provide multi-bit feedback to the end hosts.
 
-To enable it on end hosts:
+To enable it on end hosts::
 
   sysctl -w net.ipv4.tcp_congestion_control=dctcp
   sysctl -w net.ipv4.tcp_ecn_fallback=0 (optional)
···
 
  i) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
     Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
-      "Data Center TCP (DCTCP)", Data Center Networks session
+
+      "Data Center TCP (DCTCP)", Data Center Networks session"
+
       Proc. ACM SIGCOMM, New Delhi, 2010.
+
     http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
     http://www.sigcomm.org/ccr/papers/2010/October/1851275.1851192
 
 ii) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
+
       "Analysis of DCTCP: Stability, Convergence, and Fairness"
       Proc. ACM SIGMETRICS, San Jose, 2011.
+
     http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
 
 IETF informational draft:

Documentation/networking/index.rst

···
    cops
    cxacru
    dccp
+   dctcp
 
 .. only::  subproject and html