Some SEO improvements

- meta description
- empty robots.txt
- changed welcome message on home to h2

- CSS in-line fold pairs

layouts/partials/me-equation.html

@@ -8,6 +8,7 @@
   <div class="equation-part">
     <a href="https://www.wikiwand.com/en/Arch_Linux" target="_blank">
       <img src="{{ "img/arch.svg" | relURL }}" alt="linux-logo">
+      <!-- <img src="{{ "img/larbs.png" | relURL }}" alt="linux-logo"> -->
     </a>
   <p>+</p>
   </div>