Add a PUT request in the mock server to update employee data

[HKayed]

As a user, I'd like to be able to properly edit my data. Currently the edit can be done but not saved due to the non-existence of an endpoint with which we could update one's data.

Acceptance Criteria

• Investigate how the request could be added to the yaml file
• Add the request and provide the employee ID (id) as a parameter
• Test the saving of the edited data after using the new http request
• Test the retrieval of the data after the modifications made to the yaml file