docs(contribution): add guide (#3076)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

docs/app/pages/[...slug].vue

@@ -86,6 +86,14 @@ const communityLinks = computed(() => [{
   label: 'Star on GitHub',
   to: `https://github.com/nuxt/${page.value?.module === 'ui-pro' ? 'ui-pro' : 'ui'}`,
   target: '_blank'
+}, {
+  icon: 'i-heroicons-lifebuoy',
+  label: 'Contribution',
+  to: '/getting-started/contribution'
+}, {
+  label: 'Roadmap',
+  icon: 'i-heroicons-map',
+  to: '/roadmap'
 }])
 
 // const resourcesLinks = [{
@@ -136,7 +144,7 @@ const communityLinks = computed(() => [{
     <UPageBody>
       <ContentRenderer v-if="page.body" :value="page" />
 
-      <USeparator />
+      <USeparator v-if="surround?.filter(Boolean).length" />
 
       <UContentSurround :surround="(surround as any)" />
     </UPageBody>