callout styling. note and warning tags. sorting

_plugins/warning.rb

@@ -0,0 +1,17 @@
+module Jekyll
+  module Tags
+    class WarningTag < Liquid::Block
+      def render(context)
+        site = context.registers[:site]
+        converter = site.find_converter_instance(::Jekyll::Converters::Markdown)
+        output = converter.convert(super(context))
+        "<div class=\"callout callout-warning\">
+            <h3><i class=\"fa fa-warning\"></i> Warning</h3>
+            #{output}
+        </div>"
+      end
+    end
+  end
+end
+
+Liquid::Template.register_tag('warning', Jekyll::Tags::WarningTag)