Add showcase (#11)

Author: chrisgreg

bloom_site/lib/bloom_site_web/components/layouts/app.html.heex

@@ -9,20 +9,22 @@
       </p>
     </div>
     <div class="flex items-center gap-4 font-semibold leading-6 text-zinc-900">
-      <a href="https://github.com/chrisgreg/bloom" class="hover:text-zinc-700 w-8">
+      <.link navigate="/showcase" class="hover:text-zinc-700">Showcase</.link>
+      <.link navigate="/storybook" class="hover:text-zinc-700">Docs</.link>
+      <.link href="https://github.com/chrisgreg/bloom" class="hover:text-zinc-700 w-8">
         <svg class="w-8 h-8" aria-hidden="true" fill="currentColor" viewBox="0 0 24 24">
           <path
             fill-rule="evenodd"
             d="M12 2C6.477 2 2 6.484 2 12.017c0 4.425 2.865 8.18 6.839 9.504.5.092.682-.217.682-.483 0-.237-.008-.868-.013-1.703-2.782.605-3.369-1.343-3.369-1.343-.454-1.158-1.11-1.466-1.11-1.466-.908-.62.069-.608.069-.608 1.003.07 1.531 1.032 1.531 1.032.892 1.53 2.341 1.088 2.91.832.092-.647.35-1.088.636-1.338-2.22-.253-4.555-1.113-4.555-4.951 0-1.093.39-1.988 1.029-2.688-.103-.253-.446-1.272.098-2.65 0 0 .84-.27 2.75 1.026A9.564 9.564 0 0112 6.844c.85.004 1.705.115 2.504.337 1.909-1.296 2.747-1.027 2.747-1.027.546 1.379.202 2.398.1 2.651.64.7 1.028 1.595 1.028 2.688 0 3.848-2.339 4.695-4.566 4.943.359.309.678.92.678 1.855 0 1.338-.012 2.419-.012 2.747 0 .268.18.58.688.482A10.019 10.019 0 0022 12.017C22 6.484 17.522 2 12 2z"
             clip-rule="evenodd"
           />
         </svg>
-      </a>
+      </.link>
     </div>
   </div>
 </header>
 <main class="px-4 py-20 sm:px-6 lg:px-8">
-  <div class="mx-auto max-w-4xl">
+  <div class="mx-auto max-w-7xl">
     <.flash_group flash={@flash} />
     <%= @inner_content %>
   </div>