docs(context-storage): improve

docs/middleware/builtin/context-storage.md

@@ -1,6 +1,12 @@
 # Context Storage Middleware
 
-The Context Storage Middleware stores the Hono `Context` in the `AsyncLocalStorage`, to make it globally accessible. 
+The Context Storage Middleware stores the Hono `Context` in the `AsyncLocalStorage`, to make it globally accessible.
+
+::: info
+**Note** This middleware uses `AsyncLocalStorage`. The runtime should support it.
+
+**Cloudflare Workers**: To enable `AsyncLocalStorage`, add the [`nodejs_compat` or `nodejs_als` flag](https://developers.cloudflare.com/workers/configuration/compatibility-dates/#nodejs-compatibility-flag) to your `wrangler.toml` file.
+:::
 
 ## Import
 
@@ -11,6 +17,8 @@ import { contextStorage, getContext } from 'hono/context-storage'
 
 ## Usage
 
+The `getContext()` will return the current Context object if the `contextStorage()` is applied as a middleware.
+
 ```ts
 type Env = {
   Variables: {
@@ -22,9 +30,35 @@ const app = new Hono<Env>()
 
 app.use(contextStorage())
 
-app.get('/', (c) => c.text(getMessage())
+app.use(async (c, next) => {
+  c.set('message', 'Hello!')
+  await next()
+})
 
+// You can access the variable outside the handler.
 const getMessage = () => {
   return getContext<Env>().var.message
 }
+
+app.get('/', (c) => {
+  return c.text(getMessage())
+})
+```
+
+On Cloudflare Workers, you can access the bindings outside the handler.
+
+```ts
+type Env = {
+  Bindings: {
+    KV: KVNamespace
+  }
+}
+
+const app = new Hono<Env>()
+
+app.use(contextStorage())
+
+const setKV = (value: string) => {
+  return getContext<Env>().env.KV.put('key', value)
+}
 ```