fix(readme): show how to instantiate account

readme.md

@@ -22,6 +22,15 @@ Use TypeScript for best in class intellisense.
 
 letterxpress implements the LXP API documented here: [LXP API Documentation](https://www.letterxpress.de/briefe-uebertragen/api)
 
+```typescript
+import * as letterxpress from '@mojoio/letterxpress'
+
+const account = new letterxpress.LetterXpressAccount({
+  email: 'myemail@example.com',
+  apiToken: 'abcdefghijklmnop1234567890'
+})
+```
+
 ## Contribution
 
 We are always happy for code contributions. If you are not the code contributing type that is ok. Still, maintaining Open Source repositories takes considerable time and thought. If you like the quality of what we do and our modules are useful to you we would appreciate a little monthly contribution: You can [contribute one time](https://lossless.link/contribute-onetime) or [contribute monthly](https://lossless.link/contribute). :)