iw-reg: add page (#22765)

Co-authored-by: Ivan Baluta <ivanbaluta.dev@gmail.com>

pages/linux/iw-reg.md

@@ -0,0 +1,16 @@
+# iw reg
+
+> Manage WLAN regulatory domains.
+> More information: <https://wireless.docs.kernel.org/en/latest/en/users/documentation/iw.html>.
+
+- Display the current regulatory domain:
+
+`iw reg get`
+
+- Set the regulatory domain according to ISO 3166-1 alpha-2:
+
+`sudo iw reg set {{US|JP|FI|...}}`
+
+- Reload the kernel's regulatory database:
+
+`sudo iw reg reload`