Reorder sidebar nav

Author: johno

packages/gatsby-theme-mdx/src/components/sidebar.mdx

@@ -10,8 +10,8 @@
 *   [Playground <sup style={{ color: '#444', textTransform: 'uppercase' }}>*alpha*</sup>](/playground)
 *   [Guides](/guides)
     *   [Syntax highlighting](/guides/syntax-highlighting)
-    *   [Math blocks](/guides/math-blocks)
     *   [Live code editor](/guides/live-code)
+    *   [Math blocks](/guides/math-blocks)
     *   [Table of contents](/guides/table-of-contents)
     *   [Writing a plugin](/guides/writing-a-plugin)
     *   [Custom loader](/guides/custom-loader)