Add HMTL Intro (#109)

packages/learn/gatsby-config.js

@@ -30,7 +30,38 @@ module.exports = {
         path: path.resolve(__dirname, './src/introductions')
       }
     },
-    'gatsby-transformer-remark',
+    {
+      resolve: 'gatsby-transformer-remark',
+      options: {
+        plugins: [
+          {
+            resolve: 'gatsby-remark-prismjs',
+            options: {
+              // Class prefix for <pre> tags containing syntax highlighting;
+              // defaults to 'language-' (eg <pre class="language-js">).
+              // If your site loads Prism into the browser at runtime,
+              // (eg for use with libraries like react-live),
+              // you may use this to prevent Prism from re-processing syntax.
+              // This is an uncommon use-case though;
+              // If you're unsure, it's best to use the default value.
+              classPrefix: 'language-',
+              // This is used to allow setting a language for inline code
+              // (i.e. single backticks) by creating a separator.
+              // This separator is a string and will do no white-space
+              // stripping.
+              // A suggested value for English speakers is the non-ascii
+              // character '›'.
+              inlineCodeMarker: null,
+              // This lets you set up language aliases.  For example,
+              // setting this to '{ sh: "bash" }' will let you use
+              // the language "sh" which will highlight using the
+              // bash highlighter.
+              aliases: {}
+            }
+          }
+        ]
+      }
+    },
     {
       resolve: 'gatsby-plugin-google-fonts',
       options: {