chore(design) Redo the webpage

Trying to make a modern webpage. Tailwind is verbose but helps to do it
faster. I will later make a better CSS.

TODO: make dynamic links to package repository, exe, binaries... and add
a better example

src/partials/demo.html

@@ -0,0 +1,23 @@
+<section class="py-16 bg-white">
+  <div class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8">
+    <div class="text-center mb-16">
+      <h2 class="text-3xl font-bold text-gray-900 mb-4">
+        See Katenary in Action
+      </h2>
+      <p class="text-xl text-gray-600 max-w-3xl mx-auto">
+        Watch how easily you can convert Docker Compose to Helm Charts
+      </p>
+    </div>
+    <div
+      class="aspect-w-16 aspect-h-9 bg-gray-900 rounded-xl overflow-hidden shadow-lg"
+    >
+      <iframe
+        class="w-full h-96"
+        src="https://www.youtube.com/embed/RrX5jNxS9IA"
+        title="YouTube video player"
+        allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; presentation"
+        allowfullscreen
+      ></iframe>
+    </div>
+  </div>
+</section>