Build: highlight the name of the version

I find pretty hard to know what's the version of the current build on the build
details' page, so I want to make it more visible.

I'm following the same style/pattern we are following for the build id and I
like it.

Author: humitos

readthedocsext/theme/templates/builds/includes/build_name.html

@@ -50,7 +50,9 @@
     {% else %}
       {# Translators: this renders with the version name, example "Version latest" #}
       {% blocktrans trimmed with version_name=build.get_version_name %}
-        Version {{ version_name }}
+        Versions
+        <span class="divider">/</span>
+        <code class="ui grey text">{{ version_name }}</code>
       {% endblocktrans %}
     {% endif %}