Document CONFIG_SIM_NETDEV_VPNKIT

boards/sim/sim/sim/NETWORK-VPNKIT.txt

@@ -0,0 +1,24 @@
+Network support with VPNKit
+===========================
+
+The simulation can be configured to use VPNKit to provide network support.
+While this was developed for macOS, it should work on other platforms
+as well.
+
+Configuration
+-------------
+
+    CONFIG_SIM_NETDEV=y
+    CONFIG_SIM_NETDEV_TAP is not set
+    CONFIG_SIM_NETDEV_VPNKIT=y
+
+How to run
+----------
+
+You can use it as the following:
+
+    % vpnkit --ethernet /tmp/vpnkit-nuttx &
+    % ./nuttx
+
+NOTE: The unix domain socket path (/tmp/vpnkit-nuttx) is
+currently hardcoded in the code.