docs: huge migration to runtime asset cache

packages/docs/src/landing/landing-example.md

@@ -0,0 +1,19 @@
+<!-- prettier-ignore -->
+```tsx
+import * as React from "react"
+import { Embed, Button } from "reacord"
+
+function Counter() {
+  const [count, setCount] = React.useState(0)
+  return (
+    <>
+      <Embed title="Counter">
+        This button has been clicked {count} times.
+      </Embed>
+      <Button onClick={() => setCount(count + 1)}>
+        +1
+      </Button>
+    </>
+  )
+}
+```