doc: Add a man page for Wireguard VPN tunnel interfaces

Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>

Makefile

@@ -148,7 +148,8 @@ MANPAGES_5 = \
 	doc/interfaces-batman.5 \
 	doc/interfaces-bridge.5 \
 	doc/interfaces-vrf.5 \
-	doc/interfaces-vxlan.5
+	doc/interfaces-vxlan.5 \
+	doc/interfaces-wireguard.5
 
 MANPAGES_7 = \
 	doc/ifupdown-executor.7

doc/interfaces-wireguard.scd

@@ -0,0 +1,47 @@
+interfaces-wireguard(5)
+
+# NAME
+
+*interfaces-wireguard* - Wireguard extensions for the interfaces(5) file format
+
+# DESCRIPTION
+
+Wireguard is a comtemporary in-Kernel layer 3 VPN protocol implementation
+which aims to provide fast and secure tunnels. The following options
+allow to set up Wireguard VPN tunnels.
+
+# WIREGUARD-RELATED OPTIONS
+
+*wireguard-config-path* _path_
+	Denotes the absolute _path_ to the Wireguard configuration file.
+	If no path is given, _/etc/wireguard/<interface>.conf_ will be
+	used. In the latter case _use wireguard_ has to be explicitly
+	set to the interface configuration.
+
+# EXAMPLES
+
+A Wireguard VPN tunnel with explicit configuration file specified
+
+```
+auto wg-foo
+iface wg-foo
+	wireguard-config-path /etc/wireguard/foo.conf
+	#
+	address 192.0.2.23/42
+	address 2001:db8::23/64
+```
+
+A Wireguard VPN tunnel with implicit configuration file:
+
+```
+auto wg-bar
+iface wg-bar
+	use wireguard
+	#
+	address 192.0.2.23/42
+	address 2001:db8::23/64
+```
+
+# AUTHORS
+
+Maximilian Wilhelm <max@sdn.clinic>

doc/interfaces.scd

@@ -160,6 +160,9 @@ most common options are:
 	The interface is a Virtual Extensible LAN (VXLAN) tunnel
 	endpoint.
 
+*wireguard*
+	The interface is a Wireguard VPN tunnel endpoint.
+
 Check *interfaces-<option>(5)* for further informaton about a given
 option and available configuration parameters.
 
@@ -204,6 +207,7 @@ iface eth0
 *interfaces-bridge*(5)
 *interfaces-vrf*(5)
 *interfaces-vxlan*(5)
+*interfaces-wireguard*(5)
 
 # AUTHORS