Improve text about implementing missing functions (bug #40990) * missing.md: Improve text, as Felipe G. Nievinski suggested. * _config.yml, get-involved.md, index.html, missing.md: try to use jekyll variables for common URLs.

---
layout: default
---

<article class="post">

  <header class="post-header">
    <h1 class="post-title">{{ page.title }}</h1>
  </header>

  <div class="post-content">
    {{ content }}
  </div>

</article>