Update Docu: Systempassword need to be set in the headers!

[rettet-die-stille]

I think the docmentation under https://github.com/BoschSmartHome/bosch-shc-api-docs/tree/master/postman is missing the important instruction that you need to set a header "Systempassword" with the value {{system_password_base64}} if you want to add a new user.

[tobiastraxel]

The postman collection uses this header already on the request to add a new client. When using the base64 encoder on macOS, remember to use option -n: echo -n "myPassword" | base64

[sebastianharder]

The system password is mentioned in the README and is contained in the "new client" request in the Postman collection.