Make the About/"Learn more" home CTA a descriptive link

Lighthouse SEO flagged the EN "Learn more" -> /en/about-us/ link as
non-descriptive; renamed to "Learn more about MSOS". The MK/SI
equivalents were dead <button>s (no href, no JS handler) — converted
them to real links to their about-us page with descriptive text
("Дознај повеќе за МСОС" / "Več o MSOS").

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

en/index.html

@@ -265,7 +265,7 @@
             <div class="team-content">
                 <h2>Every Student Has a Story, Here’s Ours</h2>
                 <p>Curious about what MSOS is all about? This video tells our story, fast, fun, and from the heart. See what makes MSOS special in our video, and hit “Learn more” to be part of the story.</p>
-                <a href="../en/about-us/" class="btn btn-secondary">Learn more</a>
+                <a href="../en/about-us/" class="btn btn-secondary">Learn more about MSOS</a>
             </div>
         </section>