chore(doc): fix typo in readme

Author: rubenhoenle

README.md

@@ -48,7 +48,7 @@ The only thing you need is a STACKIT account and valid credentials.
 
 ## Authorization
 
-To authenticate to the SDK, you will need a [service account](https://docs.stackit.cloud/stackit/en/service-accounts-134415819.html). Create it in the STACKIT Portal an assign it the necessary permissions, e.g. `project.owner`.
+To authenticate to the SDK, you will need a [service account](https://docs.stackit.cloud/stackit/en/service-accounts-134415819.html). Create it in the STACKIT Portal and assign it the necessary permissions, e.g. `project.owner`.
 
 There are multiple ways to authenticate: