fixed README

Code-Hex · Code-Hex · commit a2d752f33202 · 2022-07-06T18:02:13.000+09:00
diff --git a/README.md b/README.md
@@ -93,6 +93,14 @@ addEventListener('fetch', (event: FetchEvent) => {
 })
 ```
 
+## Install
+
+You can install from npm registry.
+
+```
+$ npm i firebase-auth-cloudflare-workers
+```
+
 ## Docs
 
 - [API](#api)
