docs: networking: convert pktgen.txt to ReST

- add SPDX header;
- adjust title markup;
- use bold markups on a few places;
- mark code blocks and literals as such;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/index.rst

@@ -91,6 +91,7 @@ Contents:
    operstates
    packet_mmap
    phonet
+   pktgen
 
 .. only::  subproject and html
 

net/Kconfig

@@ -344,7 +344,7 @@ config NET_PKTGEN
 	  what was just said, you don't need it: say N.
 
 	  Documentation on how to use the packet generator can be found
-	  at <file:Documentation/networking/pktgen.txt>.
+	  at <file:Documentation/networking/pktgen.rst>.
 
 	  To compile this code as a module, choose M here: the
 	  module will be called pktgen.

net/core/pktgen.c

@@ -56,7 +56,7 @@
  * Integrated to 2.5.x 021029 --Lucio Maciel (luciomaciel@zipmail.com.br)
  *
  * 021124 Finished major redesign and rewrite for new functionality.
- * See Documentation/networking/pktgen.txt for how to use this.
+ * See Documentation/networking/pktgen.rst for how to use this.
  *
  * The new operation:
  * For each CPU one thread/process is created at start. This process checks

samples/pktgen/README.rst

@@ -3,7 +3,7 @@ Sample and benchmark scripts for pktgen (packet generator)
 This directory contains some pktgen sample and benchmark scripts, that
 can easily be copied and adjusted for your own use-case.
 
-General doc is located in kernel: Documentation/networking/pktgen.txt
+General doc is located in kernel: Documentation/networking/pktgen.rst
 
 Helper include files
 ====================