Fix about title wording

Author: Florent Biville

_includes/about.html

@@ -2,7 +2,7 @@
     <div class="container">
         <div class="row">
             <div class="col-sm-8 col-sm-offset-2 text-center">
-                <h2 class="section-heading">A <a href="https://www.hackergarten.net/" rel="noopener" target="_blank">Hackergarten</a> event</h2>
+                <h2 class="section-heading">A family of <a href="https://www.hackergarten.net/" rel="noopener" target="_blank">Hackergarten</a> events</h2>
                 <hr class="light">
                 <p class="text-left"><a href="https://hack-commit-pu.sh" rel="noopener" target="_blank">hack-commit-push</a> is a series of events inviting attendees to start contributing to Free/Open Source projects with the help of their maintainers.<br /> 
                 Get together, support free/open source projects by fixing issues and adding new features and most of all learn and have fun.</p>