Update SDK documentation (#20)

* Update SDK documentation

* fix doc

apps/docs/get-started/nodejs.mdx

@@ -35,6 +35,8 @@ description: "Send your mail using unsend in NodeJS"
     Get the API key from the [Unsend dashboard](https://app.unsend.dev/api-keys) and initialize the SDK
 
     ```javascript
+    import { Unsend } from "unsend";
+
     const unsend = new Unsend({ apiKey: "us_12345" });
     ```
 

packages/sdk/README.md

@@ -0,0 +1,48 @@
+# Unsend SDK
+
+## Prerequisites
+
+- [Unsend API key](https://app.unsend.dev/api-keys)
+- [Verified domain](https://app.unsend.dev/domains)
+
+## Installation
+
+### NPM
+
+```bash
+npm install unsend
+```
+
+### Yarn
+
+```bash
+yarn add unsend
+```
+
+### PNPM
+
+```bash
+pnpm add unsend
+```
+
+### Bun
+
+```bash
+bun add unsend
+```
+
+## Usage
+
+```javascript
+import { Unsend } from "unsend";
+
+const unsend = new Unsend({ apiKey: "us_12345" });
+
+unsend.emails.send({
+  to: "hello@acme.com",
+  from: "hello@company.com",
+  subject: "Unsend email",
+  html: "<p>Unsend is the best open source product to send emails</p>",
+  text: "Unsend is the best open source product to send emails",
+});
+```

packages/sdk/src/unsend.ts

@@ -27,7 +27,7 @@ export class Unsend {
 
       if (!this.key) {
         throw new Error(
-          'Missing API key. Pass it to the constructor `new Unsend("re_123")`'
+          'Missing API key. Pass it to the constructor `new Unsend("us_123")`'
         );
       }
     }