Update favicon.html

Author: fingolfin

_includes/favicon.html

@@ -9,7 +9,7 @@
   Moreover, we use alternate icons to support older browsers that don't
   support SVG favicons.
 {%- endcomment -%}
-{%- assign ver = 1 %}
+{%- assign ver = 2 %}
 <!-- Default favicon (SVG) -->
 <link rel="icon" href="{{ site.baseurl }}/assets/logo/favicon.svg?v={{ver}}" type="image/svg+xml" />