Update variables include template

docs/scripts/plugins/01-read-initial-variables.js

@@ -3,16 +3,17 @@ module.exports = plugin;
 const utils = require('./utils');
 
 function plugin() {
-  let variables = {
-    by_name: {},
-    list: [],
-  };
 
   return (files, metalsmith, done) => {
     setImmediate(done);
 
     Object.keys(files).forEach(file_path => {
       const {file_name, lines} = utils.getLines(files, file_path);
+      let variables = {
+        by_name: {},
+        list: [],
+        file_path,
+      };
 
       lines.forEach(line => {
         const variable = utils.parseLine(line);