Move kubernetes example under docs

docs/examples/kubernetes/init.bash

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -eux
+cd $(dirname $0)
+
+umask 022
+mkdir -p base/site/
+[ ! -e base/site/public.env ] && (
+    cat >base/site/public.env <<EOF
+public-hostname=localhost
+public-proto=http
+contact-email=headscale@example.com
+EOF
+)
+[ ! -e base/site/derp.yaml ] && cp ../derp.yaml base/site/derp.yaml
+
+umask 077
+mkdir -p base/secrets/
+[ ! -e base/secrets/private-key ] && (
+    wg genkey > base/secrets/private-key
+)
+mkdir -p postgres/secrets/
+[ ! -e postgres/secrets/password ] && (head -c 32 /dev/urandom | base64 -w0 > postgres/secrets/password)