docs,website: add doc for kg

This commit adds a doc for `kg`, the Kilo agent that runs on every node
in the mesh. This includes: the doc itself, files needed for the
website, and tooling to generate the document using `embedmd`.

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

docs/kg.md

@@ -0,0 +1,53 @@
+# kg
+
+`kg` is the Kilo agent that runs on every Kubernetes node in a Kilo mesh.
+It performs several key functions, including:
+* adding the node to the Kilo mesh;
+* installing CNI configuration on the node;
+* configuring the WireGuard network interface; and
+* maintaining routing table entries and iptables rules.
+
+`kg` is typically installed on all nodes of a Kubernetes cluster using a DaemonSet.
+Example manifests can be found [in the manifests directory](https://github.com/squat/kilo/tree/master/manifests).
+
+## Usage
+
+The behavior of `kg` can be configured using the command line flags listed below.
+
+[embedmd]:# (../tmp/help.txt)
+```txt
+Usage of bin/amd64/kg:
+  -backend string
+    	The backend for the mesh. Possible values: kubernetes (default "kubernetes")
+  -clean-up-interface
+    	Should Kilo delete its interface when it shuts down?
+  -cni
+    	Should Kilo manage the node's CNI configuration? (default true)
+  -cni-path string
+    	Path to CNI config. (default "/etc/cni/net.d/10-kilo.conflist")
+  -compatibility string
+    	Should Kilo run in compatibility mode? Possible values: flannel
+  -encapsulate string
+    	When should Kilo encapsulate packets within a location? Possible values: never, crosssubnet, always (default "always")
+  -hostname string
+    	Hostname of the node on which this process is running.
+  -interface string
+    	Name of the Kilo interface to use; if it does not exist, it will be created. (default "kilo0")
+  -kubeconfig string
+    	Path to kubeconfig.
+  -listen string
+    	The address at which to listen for health and metrics. (default ":1107")
+  -local
+    	Should Kilo manage routes within a location? (default true)
+  -log-level string
+    	Log level to use. Possible values: all, debug, info, warn, error, none (default "info")
+  -master string
+    	The address of the Kubernetes API server (overrides any value in kubeconfig).
+  -mesh-granularity string
+    	The granularity of the network mesh to create. Possible values: location, full (default "location")
+  -port uint
+    	The port over which WireGuard peers should communicate. (default 51820)
+  -subnet string
+    	CIDR from which to allocate addresses for WireGuard interfaces. (default "10.4.0.0/16")
+  -version
+```