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>

website/docs/kg

@@ -0,0 +1,4 @@
+---
+id: kg
+hide_title: true
+---

website/sidebars.js

@@ -12,7 +12,7 @@ module.exports = {
     {
       type: 'category',
       label: 'Reference',
-      items: ['annotations', 'kgctl'],
+      items: ['annotations', 'kg', 'kgctl'],
     },
     //Features: ['mdx'],
   ],