start work on documentation generator

docs/custom/getting_started.js

@@ -0,0 +1,8 @@
+module.exports = {
+  category: 'General',
+  name: 'Getting Started',
+  data:
+`# Welcome!
+discord.js is an easy-to-use and intuitive JavaScript library that wraps around the Discord API.
+`,
+};

docs/custom/index.js

@@ -0,0 +1,14 @@
+const files = [
+  require('./getting_started'),
+];
+
+const categories = {};
+for (const file of files) {
+  file.category = file.category.toLowerCase();
+  if (!categories[file.category]) {
+    categories[file.category] = {};
+  }
+  categories[file.category][file.name] = file.data;
+}
+
+module.exports = categories;