Add useInstance (#6)

packages/website/app/routes/guides/use-instance.md

@@ -0,0 +1,26 @@
+---
+meta:
+  title: useInstance
+  description: Using useInstance to get the current instance within a component
+---
+
+# useInstance
+
+You can use `useInstance` to get the current [instance](/guides/sending-messages) within a component. This can be used to let a component destroy or deactivate itself.
+
+```jsx
+import { Button, useInstance } from "reacord"
+
+function SelfDestruct() {
+  const instance = useInstance()
+  return (
+    <Button
+      style="danger"
+      label="delete this"
+      onClick={() => instance.destroy()}
+    />
+  )
+}
+
+reacord.send(channelId, <SelfDestruct />)
+```