feat: add blog loader

lib/loader/index.js

@@ -1,12 +1,18 @@
 const path = require('path');
 const loadConfig = require('./config');
+const loadBlog = require('./blog');
 
 module.exports = async function load(sourceDir) {
   // 1. load siteConfig
   const siteConfig = loadConfig(sourceDir);
 
-  // 2. extract metadata from markdown files
-  const metadatas = [];
+  // 2. extract data from all blog files
+  const blogDatas = await loadBlog(sourceDir);
 
-  return null; // todo
+  // 3. TODO
+
+  return {
+    siteConfig,
+    blogDatas
+  };
 };