Added count in twitter desc

Author: apavlo

templates/base.html

@@ -28,7 +28,12 @@
     <meta property="og:description" content="The on-line encyclopedia of databases systems from Carnegie Mellon University." />
     <meta property="og:image" content="{{ request.scheme }}://{{ request.get_host }}{% static 'core/images/dbdb_io_twitter.png' %}" />
     <meta name="twitter:title" content="Database of Databases" />
-    <meta name="twitter:description" content="The encyclopedia of databases systems from Carnegie Mellon University. Curated by @andy_pavlo" />
+    {% if num_systems %}
+    <meta name="twitter:description" content="Encyclopedia of {{ num_systems }} databases systems from Carnegie Mellon University. Curated by @andy_pavlo" />
+    {% else %}
+    <meta name="twitter:description" content="Encyclopedia of databases systems from Carnegie Mellon University. Curated by @andy_pavlo" />
+    {% endif %}
+    
     <meta name="twitter:image" content="{{ request.scheme }}://{{ request.get_host }}{% static 'core/images/dbdb_io_twitter.png' %}" />
     {% endblock %}