docs: landing page (#611)

Co-authored-by: Sébastien Chopin <seb@nuxt.com>

docs/layouts/default.vue

@@ -0,0 +1,5 @@
+<template>
+  <div>
+    <slot />
+  </div>
+</template>

docs/layouts/docs.vue

@@ -0,0 +1,41 @@
+<template>
+  <UMain>
+    <UContainer>
+      <UPage>
+        <template #left>
+          <UAside :links="anchors">
+            <BranchSelect />
+
+            <UNavigationTree :links="mapContentNavigation(navigation)" />
+          </UAside>
+        </template>
+
+        <slot />
+      </UPage>
+    </UContainer>
+  </UMain>
+</template>
+
+<script setup lang="ts">
+import type { NavItem } from '@nuxt/content/dist/runtime/types'
+
+const { mapContentNavigation } = useElementsHelpers()
+
+const navigation = inject<NavItem[]>('navigation')
+
+const anchors = [{
+  label: 'Documentation',
+  icon: 'i-heroicons-book-open-solid',
+  to: '/getting-started'
+}, {
+  label: 'Playground',
+  icon: 'i-simple-icons-stackblitz',
+  to: 'https://stackblitz.com/edit/nuxtlabs-ui?file=app.config.ts,app.vue',
+  target: '_blank'
+}, {
+  label: 'Releases',
+  icon: 'i-heroicons-rocket-launch-solid',
+  to: 'https://github.com/nuxtlabs/ui/releases',
+  target: '_blank'
+}]
+</script>