add migration file

src/migrations/20190629193445-make-root-page-public.js

@@ -0,0 +1,29 @@
+require('module-alias/register');
+const logger = require('@alias/logger')('growi:migrate:make-root-page-public');
+
+const mongoose = require('mongoose');
+const config = require('@root/config/migrate');
+
+module.exports = {
+  async up(db) {
+    logger.info('Apply migration');
+    mongoose.connect(config.mongoUri, config.mongodb.options);
+
+    const Page = require('@server/models/page')();
+
+    await Page.findOneAndUpdate(
+      { path: '/' },
+      {
+        grant: Page.GRANT_PUBLIC,
+        grantedUsers: [],
+        grantedGroup: null,
+      },
+    );
+
+    logger.info('Migration has successfully applied');
+  },
+
+  down(db) {
+    // do not rollback
+  },
+};