docs: networking: device drivers: convert dlink/dl2k.txt to ReST

- add SPDX header;
- mark code blocks and literals as such;
- mark lists 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/device_drivers/index.rst

@@ -36,6 +36,7 @@ Contents:
    davicom/dm9000
    dec/de4x5
    dec/dmfe
+   dlink/dl2k
 
 .. only::  subproject and html
 

drivers/net/ethernet/dlink/dl2k.c

@@ -1869,7 +1869,7 @@ Compile command:
 
 gcc -D__KERNEL__ -DMODULE -I/usr/src/linux/include -Wall -Wstrict-prototypes -O2 -c dl2k.c
 
-Read Documentation/networking/device_drivers/dlink/dl2k.txt for details.
+Read Documentation/networking/device_drivers/dlink/dl2k.rst for details.
 
 */