Todo: Complete the Swagger example response for session occurence with user

[rathorevaibhav]

Describe the task
There is a commented code in swagger docs for the session occurrence controller. We return the list of users also when making an API call for single session occurrence. This needs to be documented in the swagger response example for session occurrence single GET API.

Link to PR:
https://github.com/avantifellows/db-service-backend/pull/13/files#diff-45405f418db786746d1c8ccf9bc1b78df4a75aaad466c29ef1c1ef8cde1058f2R39-R46