pivpn: add page (#2671)

pages/linux/pivpn.md

@@ -0,0 +1,25 @@
+# pivpn
+
+> Easy security-hardened OpenVPN setup and manager.
+> Originally designed for the Raspberry Pi, but works on other Linux devices too.
+> Homepage: <http://www.pivpn.io/>.
+
+- Add a new client device:
+
+`sudo pivpn add`
+
+- List all client devices:
+
+`sudo pivpn list`
+
+- List currently connected devices and their statistics:
+
+`sudo pivpn clients`
+
+- Revoke a previously authenticated device:
+
+`sudo pivpn revoke`
+
+- Uninstall PiVPN:
+
+`sudo pivpn uninstall`