docs: networking: convert regulatory.txt to ReST

- add SPDX header;
- adjust title markup;
- 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

@@ -98,6 +98,7 @@ Contents:
    radiotap-headers
    ray_cs
    rds
+   regulatory
 
 .. only::  subproject and html
 

Documentation/networking/regulatory.rst

@@ -1,5 +1,8 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
 Linux wireless regulatory documentation
----------------------------------------
+=======================================
 
 This document gives a brief review over how the Linux wireless
 regulatory infrastructure works.
@@ -57,7 +60,7 @@ Users can use iw:
 
 http://wireless.kernel.org/en/users/Documentation/iw
 
-An example:
+An example::
 
   # set regulatory domain to "Costa Rica"
   iw reg set CR
@@ -104,7 +107,7 @@ Example code - drivers hinting an alpha2:
 
 This example comes from the zd1211rw device driver. You can start
 by having a mapping of your device's EEPROM country/regulatory
-domain value to a specific alpha2 as follows:
+domain value to a specific alpha2 as follows::
 
   static struct zd_reg_alpha2_map reg_alpha2_map[] = {
 	{ ZD_REGDOMAIN_FCC, "US" },
@@ -116,7 +119,7 @@ static struct zd_reg_alpha2_map reg_alpha2_map[] = {
 	{ ZD_REGDOMAIN_FRANCE, "FR" },
 
 Then you can define a routine to map your read EEPROM value to an alpha2,
-as follows:
+as follows::
 
   static int zd_reg2alpha2(u8 regdomain, char *alpha2)
   {
@@ -137,6 +140,8 @@ Lastly, you can then hint to the core of your discovered alpha2, if a match
 was found. You need to do this after you have registered your wiphy. You
 are expected to do this during initialization.
 
+::
+
 	r = zd_reg2alpha2(mac->regdomain, alpha2);
 	if (!r)
 		regulatory_hint(hw->wiphy, alpha2);
@@ -156,7 +161,7 @@ call regulatory_hint() with the regulatory domain structure in it.
 Bellow is a simple example, with a regulatory domain cached using the stack.
 Your implementation may vary (read EEPROM cache instead, for example).
 
-Example cache of some regulatory domain
+Example cache of some regulatory domain::
 
   struct ieee80211_regdomain mydriver_jp_regdom = {
 	.n_reg_rules = 3,
@@ -175,7 +180,7 @@ struct ieee80211_regdomain mydriver_jp_regdom = {
 	}
   };
 
-Then in some part of your code after your wiphy has been registered:
+Then in some part of your code after your wiphy has been registered::
 
 	struct ieee80211_regdomain *rd;
 	int size_of_regd;

MAINTAINERS

@@ -193,7 +193,7 @@ W:	https://wireless.wiki.kernel.org/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211.git
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git
 F:	Documentation/driver-api/80211/cfg80211.rst
-F:	Documentation/networking/regulatory.txt
+F:	Documentation/networking/regulatory.rst
 F:	include/linux/ieee80211.h
 F:	include/net/cfg80211.h
 F:	include/net/ieee80211_radiotap.h