update migration-guide (#1303)

* update toc

* update

* update

Co-authored-by: 陈志同 <[email protected]>

Author: Celia18305

tutorials/en-us/assets/Picture1.png

@@ -1,4 +1,8 @@
 - name: Contract Development
   href: /tutorials/en-us/development.md
 - name: Cross-chain Migration
-  href: /tutorials/en-us/migration.md
+  items:
+  - name: Migration Development Guideline
+    href: /tutorials/en-us/migration.md
+  - name: Migration Guideline on Migration Page
+    href: /tutorials/en-us/migration-guide.md

tutorials/en-us/assets/Picture10.png

@@ -1,4 +1,8 @@
 - name: 节点搭建
   href: /tutorials/zh-cn/candidatenodes.md
 - name: 跨链迁移
-  href: /tutorials/zh-cn/migration.md
+  items:
+  - name: 迁移开发指南
+    href: /tutorials/zh-cn/migration.md
+  - name: 迁移页面指南
+    href: /tutorials/zh-cn/migration-guide.md