add migration guide

MIGRATION.md

@@ -0,0 +1,103 @@
+# Migration Guide
+
+From `v1.x.x` to `v2.x.x`.
+
+## Contents
+
+- [Import / Require](#import--require)
+- [Routes](#routes)
+- [Fetch](#fetch)
+
+
+## Import / Require
+
+### Before
+
+```javascript
+const Router = require('@tsndr/cloudflare-worker-router')
+```
+
+
+### After
+
+```javascript
+import Router from '@tsndr/cloudflare-worker-router'
+```
+
+
+## Routes
+
+Just add curly braces.
+
+
+### Before
+
+```javascript
+// Register global middleware
+router.use((req, res, next) => {
+  res.headers.set('X-Global-Middlewares', 'true')
+  next()
+})
+
+// Simple get
+router.get('/user', (req, res) => {
+  res.body = {
+    data: {
+      id: 1,
+      name: 'John Doe'
+    }
+  }
+})
+```
+
+
+### After
+
+<pre>
+// Register global middleware
+router.use((<span style="color:rgb(225, 75, 75);font-weight:bold;">{</span> req, res, next <span style="color:rgb(225, 75, 75);font-weight:bold;">}</span>) => {
+  res.headers.set('X-Global-Middlewares', 'true')
+  next()
+})
+
+// Simple get
+router.get('/user', (<span style="color:rgb(225, 75, 75);font-weight:bold;">{</span> req, res <span style="color:rgb(225, 75, 75);font-weight:bold;">}</span>) => {
+  res.body = {
+    data: {
+      id: 1,
+      name: 'John Doe'
+    }
+  }
+})
+</pre>
+
+
+## Fetch / `router.handle()`
+
+Be aware that with `v2.0.0` the parameters of `router.handle()` changed.
+
+
+### Before
+
+`router.handle(request, extend = {})`
+
+```javascript
+// Listen Cloudflare Workers Fetch Event
+addEventListener('fetch', event => {
+  event.respondWith(router.handle(event.request))
+})
+```
+
+
+### After
+
+`router.handle(env, request, extend = {})`
+
+<pre>
+// Listen Cloudflare Workers Fetch Event
+export default {
+  async fetch(request, env, ctx) {
+    return router.handle(<span style="color:rgb(225, 75, 75);font-weight:bold;">env</span>, request)
+  }
+}
+</pre>