post https://uat.finserve.africa/authentication/api/v3/authenticate/merchant
After you generate you API key 
you will use this service to enable your application or service (or organization) access the Jenga resources [smart way of saying 'Jenga services'] you have been granted access to
200 Success Response Schema
| Field Name | Field Type | Field Description |
|---|---|---|
accessToken | string | |
refreshToken | string | |
expiresIn | string | |
issuedAt | string | |
tokenType | string |