illumos: update README

contrib/smf/README → contrib/smf/README.md

@@ -4,18 +4,20 @@ WireGuard for SMF
 The example `wg-quick.xml` file may be used for running wg-quick(8)
 using SMF.
 
-If your host runs multiples zones that use wireguard,
-because of the current state of the illumos TUN driver
-it is recommended to use higher numbered tunN devices to avoid
-conflicting with auto-assigned TUN devices.
-
 Usage
 -----
 
-# svccfg import wg-quick.xml
-# svccfg -s svc:/vpn/wg-quick add tun10
-# svcadm enable wg-quick:tun10
+Choose a name for you wg-quick config. It can be pretty much any simple string.
+It will be used for naming your config file and your SMF service instance name.
+The underlying tun device will be allocated dynamically.
 
+Create `/etc/wireguard/<something>.conf`
+
+```
+# svccfg import wg-quick.xml
+# svccfg -s svc:/vpn/wg-quick add something
+# svcadm enable wg-quick:something
+```
 
 Helpful references
 ------------------